Thermoelectric devices and systems

ABSTRACT

The present disclosure provides wearable electronic devices with thermoelectric devices. The wearable electronic device may comprise a user interface for displaying information to a user. The thermoelectric device may comprise a heat collecting unit, a thermoelectric element, and a heat expelling unit. During use, the thermoelectric element may generate power upon the flow of thermal energy from the heat collecting unit, across the thermoelectric element, and to the heat expelling unit.

CROSS-REFERENCE

This application is a continuation of U.S. application Ser. No.16/687,291, filed Nov. 18, 2019, which is a continuation of U.S.application Ser. No. 16/354,772, filed Mar. 15, 2019, which is acontinuation of U.S. application Ser. No. 15/585,376, filed May 3, 2017,now U.S. Pat. No. 10,290,796, which claims priority to and benefit ofU.S. Provisional Patent Application No. 62/331,404, filed May 3, 2016,U.S. Provisional Patent Application No. 62/408,015, filed Oct. 13, 2016,and U.S. Provisional Patent Application No. 62/421,120, filed Nov. 11,2016, each of which is entirely incorporated herein by reference.

BACKGROUND

Over 15 Terawatts of heat is lost to the environment annually around theworld by heat engines that require petroleum as their primary fuelsource. This is because these engines only convert about 30 to 40% ofpetroleum's chemical energy into useful work. Waste heat generation isan unavoidable consequence of the second law of thermodynamics.

The term “thermoelectric effect” encompasses the Seebeck effect, Peltiereffect and Thomson effect. Solid-state cooling and power generationbased on thermoelectric effects typically employ the Seebeck effect orPeltier effect for power generation and heat pumping. The utility ofsuch conventional thermoelectric devices is, however, typically limitedby their low coefficient-of-performance (COP) (for refrigerationapplications) or low efficiency (for power generation applications).

Thermoelectric device performance may be captured by a so-calledthermoelectric figure-of-merit, Z=S² σ/k, where ‘S’ is the Seebeckcoefficient, ‘a’ is the electrical conductivity, and ‘k’ is thermalconductivity. Z is typically employed as the indicator of the COP andthe efficiency of thermoelectric devices—that is, COP scales with Z. Adimensionless figure-of-merit, ZT, may be employed to quantifythermoelectric device performance, where ‘T’ can be an averagetemperature of the hot and the cold sides of the device.

Applications of conventional semiconductor thermoelectric coolers arerather limited, as a result of a low figure-of-merit, despite manyadvantages that they provide over other refrigeration technologies. Incooling, low efficiency of thermoelectric devices made from conventionalthermoelectric materials with small figure-of-merit limits theirapplications in providing efficient thermoelectric cooling.

SUMMARY

Although there are thermoelectric devices currently available,recognized herein are various limitations associated with suchthermoelectric devices. For example, some thermoelectric devicescurrently available may not be flexible and able to conform to objectsof various shapes, making it difficult to maximize a surface area forheat transfer. As another example, some thermoelectric devices currentlyavailable are substantially thick and not suitable for use in electronicdevices that require more compact thermoelectric devices.

In an aspect, a wearable electronic device comprises an electronicdisplay with a user interface for displaying information to a user; anda power management unit operatively coupled with the electronic display,where the power management unit comprises an energy storage device andat least one thermoelectric device in electrical communication with theenergy storage device, where the thermoelectric device comprises (i) aheat collecting unit that rests adjacent to a body surface of the user,which heat collecting unit collects thermal energy from the body surfaceof the user, (ii) a thermoelectric element in thermal communication withthe heat collecting unit, and (iii) a heat expelling unit in thermalcommunication with the thermoelectric element, which heat expelling unitexpels thermal energy from the thermoelectric element, where during usethe thermoelectric element generates power upon flow of thermal energyfrom the heat collecting unit, across the thermoelectric element and tothe heat expelling unit, wherein at least a portion of the power isstored in the energy storage device.

In some embodiments, the wearable electronic device is integrated withthe power management unit. In some embodiments, the power managementunit provides at least about 10% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 20% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 30% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 40% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 60% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 80% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitfurther comprises an external power unit for providing external power tocharge the energy storage device.

In some embodiments, the wearable electronic device further comprises acasing containing the electronic display and the power management unit.In some embodiments, the heat expelling unit is at a side portion of thecasing. In some embodiments, the casing is in thermal communication withthe heat collecting unit. In some embodiments, the casing is in thermalcommunication with the heat expelling unit. In some embodiments, thecasing is in thermal communication with both of the heat collecting unitand the heat expelling unit. In some embodiments, the casing issubstantially waterproof or water resistant.

In some embodiments, the casing comprises lugs. In some embodiments, thelugs are in thermal communication with the heat expelling unit. In someembodiments, the lugs dissipate heat. In some embodiments, the lugs donot dissipate heat.

In some embodiments, the casing further comprises a bottom subassembly.In some embodiments, the bottom subassembly comprises a conductiveplate. In some embodiments, the bottom subassembly comprises thethermoelectric element. In some embodiments, the bottom subassemblycomprises a conductive backing. In some embodiments, during use theconductive backing is in thermal communication with the body of theuser. In some embodiments, the bottom subassembly snaps into the casing.In some embodiments, the bottom subassembly comprises threads and thebottom subassembly threads into the casing. In some embodiments, thethreads are thermally conductive.

In some embodiments, the heat expelling unit includes one or more heatsinks. In some embodiments, the one or more heat sinks are heat fins. Insome embodiments, thermal communication between the thermoelectricelement and the heat expelling unit is provided by at least one heatpipe. In some embodiments, thermal communication between thethermoelectric element and the heat expelling unit is provided by a heatspreader plate.

In some embodiments, the wearable electronic device further comprises acontrol unit operatively coupled to the electronic display and the powermanagement unit, where the control unit regulates the display of theinformation on the user interface. In some embodiments, the wearableelectronic device is a watch. In some embodiments, the user interface isa graphical user interface. In some embodiments, the user interface isan analog user interface. In some embodiments, the power management unitis included in a clasp that secures the electronic display to the bodysurface of the user. In some embodiments, the wearable electronic devicefurther comprises a flexible circuit operatively coupled and inelectrical communication with the electronic display and the powermanagement unit. In some embodiments, the flexible circuit is a flexibleprinted circuit. In some embodiments, the flexible circuit is aflexible-flat cable.

In some embodiments, the wearable electronic device further comprisesone or more power generation units in electrical communication with theenergy store device. In some embodiments, the one or more powergeneration units are selected from the group consisting of a solar cell,an inductive coupling unit, a radio frequency coupling unit, and akinetic power generation unit.

In an aspect, a method for using a wearable electronic device comprisesactivating the wearable electronic device, where the wearable electronicdevice comprises an electronic display with a user interface fordisplaying information to a user and a power management unit operativelycoupled with the electronic display, where the power management unitcomprises an energy storage device and at least one thermoelectricdevice in electrical communication with the energy storage device, wherethe thermoelectric device comprises (i) a heat collecting unit thatrests adjacent to a body surface of the user, which heat collecting unitcollects thermal energy from the body surface of the user, (ii) athermoelectric element in thermal communication with the heat collectingunit, and (iii) a heat expelling unit in thermal communication with thethermoelectric element, which heat expelling unit expels thermal energyfrom the thermoelectric element; and using the thermoelectric element togenerate power upon flow of thermal energy from the heat collectingunit, across the thermoelectric element and to the heat expelling unit,where at least a portion of the power is stored in the energy storagedevice.

In some embodiments, the wearable electronic device is integrated withthe power management unit. In some embodiments, the power managementunit provides at least about 10% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 20% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 30% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 40% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 60% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitprovides at least about 80% of a power requirement of the wearableelectronic device. In some embodiments, the power management unitfurther comprises an external power unit for providing external power tocharge the energy storage device.

In some embodiments, the wearable electronic device further comprises acasing containing the electronic display and the power management unit.In some embodiments, the heat expelling unit is at a side portion of thecasing. In some embodiments, the casing is in thermal communication withthe heat collecting unit. In some embodiments, the casing is in thermalcommunication with the heat expelling unit. In some embodiments, thecasing is in thermal communication with both of the heat collecting unitand the heat expelling unit. In some embodiments, the casing issubstantially waterproof or water resistant.

In some embodiments, the casing comprises lugs. In some embodiments, thelugs are in thermal communication with the heat expelling unit. In someembodiments, the lugs dissipate heat. In some embodiments, the lugs donot dissipate heat.

In some embodiments, the casing further comprises a bottom subassembly.In some embodiments, the bottom subassembly comprises a conductiveplate. In some embodiments, the bottom subassembly comprises thethermoelectric element. In some embodiments, the bottom subassemblycomprises a conductive backing. In some embodiments, during use theconductive backing is in thermal communication with the body of theuser. In some embodiments, the bottom subassembly snaps into the casing.In some embodiments, the bottom subassembly comprises threads and thebottom subassembly threads into the casing. In some embodiments, thethreads are thermally conductive.

In some embodiments, the heat expelling unit includes one or more heatsinks. In some embodiments, the one or more heat sinks are heat fins. Insome embodiments, thermal communication between the thermoelectricelement and the heat expelling unit is provided by at least one heatpipe. In some embodiments, thermal communication between thethermoelectric element and the heat expelling unit is provided by a heatspreader plate.

In some embodiments, the wearable electronic device further comprises acontrol unit operatively coupled to the electronic display and the powermanagement unit, where the control unit regulates the display of theinformation on the user interface. In some embodiments, the wearableelectronic device is a watch. In some embodiments, the user interface isa graphical user interface. In some embodiments, the user interface isan analog user interface. In some embodiments, the power management unitis included in a clasp that secures the electronic display to the bodysurface of the user. In some embodiments, the wearable electronic devicefurther comprises a flexible circuit operatively coupled and inelectrical communication with the electronic display and the powermanagement unit. In some embodiments, the flexible circuit is a flexibleprinted circuit. In some embodiments, the flexible circuit is aflexible-flat cable.

In some embodiments, the wearable electronic device further comprisesone or more power generation units in electrical communication with theenergy store device. In some embodiments, the one or more powergeneration units are selected from the group consisting of a solar cell,an inductive coupling unit, a radio frequency coupling unit, and akinetic power generation unit.

In an aspect, a method for manufacturing a wearable electronic device,comprising (i) assembling an electronic display with a user interfacefor displaying information to a user, and (ii) assembling a powermanagement unit to yield the wearable electronic device, where the powermanagement unit is operatively coupled with the electronic display,wherein the power management unit comprises an energy storage device andat least one thermoelectric device in electrical communication with theenergy storage device, where the thermoelectric device comprises (i) aheat collecting unit that rests adjacent to a body surface of the user,which heat collecting unit collects thermal energy from the body surfaceof the user, (ii) a thermoelectric element in thermal communication withthe heat collecting unit, and (iii) a heat expelling unit in thermalcommunication with the thermoelectric element, which heat expelling unitexpels thermal energy from the thermoelectric element, where thewearable device is configured such that, during use, the thermoelectricelement generates power upon flow of thermal energy from the heatcollecting unit, across the thermoelectric element, and to the heatexpelling unit, where at least a portion of the power is stored in theenergy storage device.

In some embodiments, the wearable electronic device comprises a casingcontaining the electronic display and the power management unit. In someembodiments, the casing comprises a top side and a bottom side andwherein the electronic display is disposed adjacent to the top side ofthe casing. In some embodiments, the electronic display and the powermanagement unit are loaded into the casing from the top side of thecasing. In some embodiments, the electronic display and the powermanagement unit are loaded into the casing from the bottom side of thecasing.

Additional aspects and advantages of the present disclosure will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only illustrative embodiments of thepresent disclosure are shown and described. As will be realized, thepresent disclosure is capable of other and different embodiments, andits several details are capable of modifications in various obviousrespects, all without departing from the disclosure. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings (also “figure” and “FIG.” herein), of which:

FIG. 1 shows an exploded view of a wearable device, in accordance withan embodiment of the present disclosure;

FIG. 2 shows a section view of the wearable device of FIG. 1, inaccordance with an embodiment of the present disclosure;

FIG. 3A is a top view of the case top heat sink of the wearable deviceof FIG. 1; FIG. 3B is an isometric view of the case top heat sink of thewearable device of FIG. 1; FIG. 3C is a right side view of the case topheat sink of the wearable device of FIG. 1; FIG. 3D is a front side viewof the case top heat sink of the wearable device of FIG. 1; FIG. 3E is abottom view of the case top heat sink of the wearable device of FIG. 1;

FIG. 4A is a top view of the case back conductor of the wearable deviceof FIG. 1; FIG. 4B is an isometric view of the case back conductor ofthe wearable device of FIG. 1; FIG. 4C are side views of the case backconductor of the wearable device of FIG. 1; FIG. 4D is a bottom view ofthe case back conductor of the wearable device of FIG. 1;

FIG. 5A is a top view of the wearable device of FIG. 1; FIG. 5B is aleft side view of the wearable device of FIG. 1; FIG. 5C is a bottomview of the wearable device of FIG. 1;

FIG. 6 shows a thermoelectric device having a plurality of elements;

FIG. 7 is a schematic perspective view of a thermoelectric element, inaccordance with an embodiment of the present disclosure;

FIG. 8 is a schematic top view of the thermoelectric element of FIG. 7,in accordance with an embodiment of the present disclosure;

FIG. 9 is a schematic side view of the thermoelectric element of FIGS. 7and 8, in accordance with an embodiment of the present disclosure;

FIG. 10 is a schematic perspective view of a thermoelectric element, inaccordance with an embodiment of the present disclosure.

FIG. 11 is a schematic top view of the thermoelectric element of FIG.10, in accordance with an embodiment of the present disclosure;

FIG. 12 is a schematic perspective view of a thermoelectric devicecomprising elements having an array of wires, in accordance with anembodiment of the present disclosure;

FIG. 13 is a schematic perspective view of a thermoelectric devicecomprising elements having an array of holes, in accordance with anembodiment of the present disclosure;

FIG. 14 is a schematic perspective view of a thermoelectric devicecomprising elements having an array of holes that are orientedperpendicularly with respect to the vector V, in accordance with anembodiment of the present disclosure;

FIG. 15 schematically illustrates a method for manufacturing a flexiblethermoelectric device comprising a plurality of thermoelectric elements;

FIG. 16 shows a computer system that is programmed or otherwiseconfigured to implement methods and systems of the present disclosure,such as facilitating the formation of thermoelectric devices of thepresent disclosure;

FIG. 17 shows an exploded view of a wearable device, in accordance withan embodiment of the present disclosure;

FIG. 18A is a top view of the wearable device of FIG. 17; FIG. 18B is aperspective view of the wearable device of FIG. 17; FIG. 18C is a frontview of the wearable device of FIG. 17; FIG. 18D is a side view of thewearable device of FIG. 17;

FIG. 19A is a cross-sectional side view of the wearable device of FIG.17; FIG. 19B is a front view of the wearable device of FIG. 17;

FIG. 20A is a perspective view of the wearable device of FIG. 17 withheatsink fins;

FIG. 20B is a side view of the wearable device of FIG. 17 with heatsinkfins; FIG. 20C is a side view of the wearable device of FIG. 17 withoutheatsink fins;

FIG. 21A is a cross-sectional side view of a wearable device, inaccordance with an embodiment of the present disclosure; FIG. 21B is afront view of the wearable device shown in cross-section in FIG. 21A;

FIG. 22 is a perspective view of the wearable device of FIG. 21A;

FIG. 23A is a perspective view of the wearable device of FIG. 21A; FIG.23B is a detail view corresponding to FIG. 23A;

FIG. 24 is an expanded side view of the wearable device of FIG. 21A;

FIG. 25A is a perspective view of the wearable device of FIG. 21A; FIG.25B is a side view of the wearable device of FIG. 21A;

FIG. 26A is a perspective view of an alternative embodiment of thewearable device of FIG. 21A; and FIG. 26B is a side view of analternative embodiment of the wearable device of FIG. 21A;

FIG. 27A is a perspective view of an alternative embodiment of thewearable device of FIG. 1; FIG. 27B is a back view of an alternativeembodiment of the wearable device of FIG. 1;

FIG. 27C is a top view of an alternative embodiment of the wearabledevice of FIG. 1; FIG. 27D is a left side view of an alternativeembodiment of the wearable device of FIG. 1; FIG. 27E is a front view ofan alternative embodiment of the wearable device of FIG. 1; FIG. 27F isa right side view of an alternative embodiment of the wearable device ofFIG. 1; and FIG. 27G is a bottom view of an alternative embodiment ofthe wearable device of FIG. 1;

FIG. 28A is a top view of an exemplary top loading wearable device; FIG.28B is a cross-sectional view of the components of an exemplary toploading wearable device; FIG. 28C is an exploded view of an exemplarytop loading wearable device;

FIG. 29A is a top view of an alternative embodiment of a top loadingwearable device;

FIG. 29B is a cross-sectional view of the components of an alternativeembodiment of a top loading wearable device; FIG. 29C is an explodedview of an alternative embodiment of a top loading wearable device;

FIG. 30A is a top view of an alternative embodiment of a top loadingwearable device;

FIG. 30B is a cross-sectional view of the components of an alternativeembodiment of a top loading wearable device; FIG. 30C is an explodedview of an alternative embodiment of a top loading wearable device;

FIG. 31A is a top view of an exemplary bottom loading wearable device;FIG. 31B is a cross-sectional view of the components of an exemplarybottom loading wearable device; FIG. 31C is an exploded view of anexemplary bottom loading wearable device;

FIG. 32A is a top view of an alternative embodiment of a bottom loadingwearable device; FIG. 32B is a cross-sectional view of the components ofan alternative embodiment of a bottom loading wearable device; FIG. 32Cis an exploded view of the of an alternative embodiment of a bottomloading wearable device; FIG. 32D is an exploded view of an electronicsand display subassembly of an alternative embodiment of a bottom loadingwearable device; FIG. 32E is an exploded view of a case bottomsubassembly of an alternative embodiment of a bottom loading wearabledevice;

FIG. 33A is a top view of an alternative embodiment of a bottom loadingwearable device; FIG. 33B is a cross-sectional view of the components ofan alternative embodiment of a bottom loading wearable device; FIG. 33Cis an exploded view of the full assembly of an alternative embodiment ofa bottom loading wearable device; and FIG. 33D is an exploded view of anelectronics and display subassembly of an alternative embodiment of abottom loading wearable device; FIG. 33E is an exploded view of a casebottom subassembly of an alternative embodiment of a bottom loadingwearable device.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and describedherein, it will be obvious to those skilled in the art that suchembodiments are provided by way of example only. Numerous variations,changes, and substitutions may occur to those skilled in the art withoutdeparting from the invention. It should be understood that variousalternatives to the embodiments of the invention described herein may beemployed.

The term “nanostructure,” as used herein, generally refers to structureshaving a first dimension (e.g., width) along a first axis that is lessthan about 1 micrometer (“micron”) in size. Along a second axisorthogonal to the first axis, such nanostructures can have a seconddimension from nanometers or smaller to microns, millimeters or larger.In some cases, the dimension (e.g., width) is less than about 1000nanometers (“nm”), or 500 nm, or 100 nm, or 50 nm, or smaller.Nanostructures can include holes formed in a substrate material. Theholes can form a mesh having an array of holes. In other cases,nanostructure can include rod-like structures, such as wires, cylindersor box-like structure. The rod-like structures can have circular,elliptical, triangular, square, rectangular, pentagonal, hexagonal,heptagonal, octagonal or nonagonal, or other cross-sections.

The term “nanohole,” as used herein, generally refers to a hole, filledor unfilled, having a width or diameter less than or equal to about 1000nanometers (“nm”), or 500 nm, or 100 nm, or 50 nm, or smaller. Ananohole filled with a metallic, semiconductor, or insulating materialcan be referred to as a “nanoinclusion.”

The term “nanowire,” as used herein, generally refers to a wire or otherelongate structure having a width or diameter that is less than or equalto about 1000 nm, or 500 nm, or 100 nm, or 50 nm, or smaller.

The term “n-type,” as used herein, generally refers to a material thatis chemically doped (“doped”) with an n-type dopant. For instance,silicon can be doped n-type using phosphorous or arsenic.

The term “p-type,” as used herein, generally refers to a material thatis doped with a p-type dopant. For instance, silicon can be doped p-typeusing boron or aluminum.

The term “metallic,” as used herein, generally refers to a substanceexhibiting metallic properties. A metallic material can include one ormore elemental metals.

The term “monodisperse,” as used herein, generally refers to featureshaving shapes, sizes (e.g., widths, cross-sections, volumes) ordistributions (e.g., nearest neighbor spacing, center-to-center spacing)that are similar to one another. In some examples, monodisperse features(e.g., holes, wires) have shapes or sizes that deviate from one anotherby at most about 20%, 15%, 10%, 5%, 4%, 3%, 2%, 1%, 0.5%, or 0.1%. Insome cases, monodisperse features are substantially monodisperse.

The term “etching material,” as used herein, generally refers to amaterial that facilitates the etching of substrate (e.g., semiconductorsubstrate) adjacent to the etching material. In some examples, anetching material catalyzes the etching of a substrate upon exposure ofthe etching material to an oxidizing agent and a chemical etchant.

The term “etching layer,” as used herein, generally refers to a layerthat comprises an etching material. Examples of etching materialsinclude silver, platinum, chromium, molybdenum, tungsten, osmium,iridium, rhodium, ruthenium, palladium, copper, nickel and other metals(e.g., noble metals), or any combination thereof, or any non-noble metalthat can catalyze the decomposition of a chemical oxidant, such as, forexample, copper, nickel, or combinations thereof.

The term “etch block material,” as used herein, generally refers to amaterial that blocks or otherwise impedes the etching of a substrateadjacent to the etch block material. An etch block material may providea substrate etch rate that is reduced, or in some cases substantiallyreduced, in relation to a substrate etch rate associated with an etchingmaterial. The term “etch block layer,” as used herein, generally refersto a layer that comprises an etch block material. An etch block materialcan have an etch rate that is lower than that of an etching material.

The term “reaction space,” as used herein, generally refers to anyenvironment suitable for the formation of a thermoelectric device or acomponent of the thermoelectric device. A reaction space can be suitablefor the deposition of a material film or thin film adjacent to asubstrate, or the measurement of the physical characteristics of thematerial film or thin film. A reaction space may include a chamber,which may be a chamber in a system having a plurality chambers. Thesystem may include a plurality of fluidically separated (or isolated)chambers. The system may include multiple reactions spaces, with eachreaction space being fluidically separated from another reaction space.A reaction space may be suitable for conducting measurements on asubstrate or a thin film formed adjacent to the substrate.

The term “current density,” as used herein, generally refers to electric(or electrical) current per unit area of cross section, such as thecross section of a substrate. In some examples, current density iselectric current per unit area of a surface of a semiconductorsubstrate.

The term “adjacent” or “adjacent to,” as used herein, includes ‘nextto’, ‘adjoining’, ‘in contact with’, and ‘in proximity to’. In someinstances, adjacent components are separated from one another by one ormore intervening layers. The one or more intervening layers may have athickness less than about 10 micrometers (“microns”), 1 micron, 500nanometers (“nm”), 100 nm, 50 nm, 10 nm, 1 nm, 0.5 nm or less. Forexample, a first layer adjacent to a second layer can be in directcontact with the second layer. As another example, a first layeradjacent to a second layer can be separated from the second layer by atleast a third layer.

Wearable Devices with Thermoelectric Modules

Another aspect of the present disclosure provides a wearable electronicdevice (e.g., watch) with at least one thermoelectric module or unit.Such thermoelectric module or unit may be used to provide at least someor all of the power for use by the wearable electronic device. Theelectronic device may be a watch, such as a smart watch. Thethermoelectric module or unit may be flexible.

The wearable electronic device may be wearable on various body parts ofa user. For example, the wearable electronic device may be wearable onan arm, hand, wrist, foot, ankle, or neck of the user, or an article ofclothing of or other object worn by the user. The wearable electronicdevice may be substantially waterproof or water resistant. In somecases, the wearable electronic device may be water resistant but notwaterproof.

The wearable electronic device may include a power management unit thatincludes one or more thermoelectric devices and, in some cases, anenergy storage device, such as a battery. The battery may be a solidstate battery (e.g., lithium ion battery).

The wearable electronic device may include a user interface. The userinterface may be a digital or analog user interface. The user interfacemay be a graphical user interface.

The wearable electronic device may be charged by the one or morethermoelectric devices. The one or more thermoelectric devices mayprovide at least about 10%, at least about 20%, at least about 30%, atleast about 40%, at least about 50%, at least about 60%, at least about70%, at least about 80%, at least about 90%, or more of the powerrequirement of the wearable electronic device. The wearable electronicdevice may be charged by one or more external or alternate sources ofenergy. The wearable electronic device may be charged by both thethermoelectric device and an alternate energy source. The wearableelectronic device may be charged by both the thermoelectric and anexternal energy source. External or alternate sources of energy mayinclude wired charging, inductive charging, radio frequency (RF)charging, solar charging, and kinetic charging. The wearable electronicdevice may be at least partially charged using a charging connector thatdirectly attaches to a power management unit of the wearable electronicdevice. The wearable electronic device may be at least partially chargedusing an inductive unit in electrical communication with the powermanagement unit. The inductive unit may generate power for the powermanagement unit and/or energy storage device upon coupling to anexternal magnetic field. The wearable electronic device may be at leastpartially charged using a RF charging unit in electrical communicationwith the power management unit. The RF charging unit may generate powerfor the power management unit and/or energy storage device upon couplingto a RF transmitter. The wearable electronic device may be at leastpartially charged using solar cells in electrical communication with thepower management unit. The solar cells may generate power for the powermanagement unit and/or energy storage device upon exposure to light. Thewearable electronic device may be at least partially charged using akinetic power generation unit in electrical communication with the powermanagement unit. The kinetic power generation unit may generate powerfor the power management unit and/or energy storage device upon motionof a user's body.

The wearable device may include one or more heat collecting units, oneor more thermoelectric elements, and one or more heat expelling units.The one or more heat collecting units may rest adjacent to a bodysurface of a user when the wearable device is donned, and may comprise acase back conductor, and upper body heat conductor plate, a lower bodyheat conductor plate, and one or more body heat conductor nodes. The oneor more thermoelectric elements may be in thermal communication with theone or more heat collecting units. The one or more thermoelectricelements may also be in thermal communication with the one or more heatexpelling units. Thermal communication between the thermoelectricelements and the heat expelling units may be provided by a heat pipe, avapor chamber, a heat spreader plate, or a combination thereof. The oneor more heat expelling units may expel thermal energy from the one ormore thermoelectric elements, and may comprise a case top heat sink, atop side heat sink, a bottom side heat sink, and one or more externalheat sink nodes.

Reference will now be made to the figures, wherein like numerals referto like parts throughout. It will be appreciated that the figures andfeatures therein are not necessarily drawn to scale.

FIG. 1 shows an exploded view of a wearable device 100. The wearabledevice 100 in the illustrated example is a watch. The wearable device100 may include one or more of a top glass 101, a display retainer 102,an electronic display 103, a main printed circuit board (PCB) 104, abattery 105, a retaining ring 106, one or more standoffs 107, one ormore captive nuts 108, a case top heat sink 109, one or more spring bars110, a watch button 111, a button spring 112, an insulator spacer 113, aflexible printed circuit 114, one or more thermoelectric generators(TEGs) 115, a vibration motor (VIB) 116, an insulator ring 117, one ormore cosmetic screws 118, a case back conductor 119, and one or moreassembly screws 120. The TEGs 115 may be any thermoelectric module ormaterial described herein.

The one or more TEGs 115 may be in thermal communication with the casetop heat sink 109 through a thermal conducting medium. In some examples,the one or more TEGs 115 are in thermal communication with the case topeheat sink 109 through at least one heat pipe or vapor chamber. The heatpipe or vapor chamber may serve to expel thermal energy from the TEGs115 more effectively than bulk thermal conductors.

The wearable device 100 may be coupled to a body part of a user, such asa hand of a user. During use, thermal energy may flow from a hot side ofthe wearable device 100 through the TEGs 115 to a cold side of thewearable device 100. Upon the flow of thermal energy, the TEGs 115 maygenerate power that may be stored as electrical energy in the battery105, directed to the main PCB 104, and/or used by the electronic display103.

The main PCB 104 may include one or more central processing units(CPUs). The CPUs may be coupled to the electronic display 103 to presentinformation to a user, such as time, electronic mail, or notifications,or the like.

The top glass 101 may be formed of a material which magnifies an image,such as a lens. The watch lens may be a transparent glass or plasticcomponent which may be adhered to a recessed groove in the top of thecase top heat sink 109. The watch lens may cover the top of the assemblyand hold the internal components inside of the case top. Using paint, adecal, silk screen, pad printing or similar, a mask may be created toselectively expose or hide certain internal components.

The display retainer 102 may have a cutout which allows the displayretainer 102 to complementarily receive the outer perimeter of theelectronic display 103. The outer perimeter of the display retainer 102may also be notched so as to be complementarily received by a matchingkey feature in the case top heat sink 109. When assembled, this mayallow the display retainer 102 to locate and lock the electronic display103 in a plane parallel to the top surface of the watch lens 101.

The electronic display 103 may be a low-power screen which displays thegraphical user interface. The electronic display 103 may be a capacitivetouchscreen or a resistive touchscreen. As an alternative, theelectronic display 103 may be a passive display.

The main printed circuit board (PCB) 104 may include one or more ofelectrical components, wiring, and firmware necessary for powermanagement, sensing, display, button inputs, diagnostics, and/orvibration outputs. The main PCB 104 may include an onboard energystorage device.

The battery 105 may provide energy storage for the electrical system.The battery 105 may be charged by electrical energy that is generated bythe TEGs 115. The battery 105 may be charged by an external powersource, such as electrical energy from a power grid.

The retaining ring 106 may be an E-style external side-mount ring whichseats in a groove in the watch button. The retaining ring 106 may fastenthe watch button 111 to the case top.

The one or more standoffs 107 may be used as spacers to hold the mainPCB 104 off of the watch body pieces. The top edges of these standoffs107 may also support the bottom of the electronic display, maintaining aspecified separation between the electronic display 103, the main PCB104, and the case top. In the illustrated example, there are fourstandoffs 107, but other numbers of standoffs may be used.

The one or more captive nuts 108 may be recessed in the case top heatsink. Captive nuts 108 may comprise inserts which allow the assemblyscrews 120 to be threaded into place. In the illustrated example, thereare four captive nuts 108, but other numbers of captive nuts may beused.

The case top heat sink 109 may include a highly conductive body which isexposed to the ambient air. A thermal contact plane with a smooth andflat bottom surface may be pressed against the “cold side” of the TEGs115. This thermal contact plane creates a thermal pathway between theTEG “cold side” and the ambient air. The case top may act as a heatsink, minimizing the temperature gradient between the ambient air andthe TEG “cold side”. The external ridge and groove features increase theexposed surface area which improves the heat transfer to air. The casetop may also hold one or more of an electronic display 103, a main PCB104, a battery 105, and a watch lens. The case top may include lugswhich allow for the attachment of a watch strap via the spring bars 110.The lugs may be in thermal communication with the heat expelling unit.The lugs may dissipate heat. Alternatively, or in addition to, the lugsmay not dissipate heat. The case top may include features forpositioning and guiding the watch button 111. The case top may beproduced from a material with a high coefficient of thermalconductivity, such as, for example, an aluminum or copper alloy.

The one or more spring bars 110 may be used to attach and detachdifferent watch bands to the assembly. In the illustrated example, thereare two spring bars 110, but other numbers of spring bars may be used.

The watch button 111 may transfer a push input from the user into anedge-mounted SMT switch on the main PCB 104. Depressing the watch button111 compresses the button spring 112. The watch button 111 may be aninterface element, which is produced from a material with a highcoefficient of thermal conductivity such as an aluminum or copper alloy.The watch button 111 may be used for one or more of menu navigation,user-interface manipulation, and power cycling.

The button spring 112 may act as a pre-load which keeps the watch button111 extended and/or not in direct contact with the switch on the mainPCB 104, thereby minimizing accidental presses by the user of thewearable device. The button spring 112 may be held in place between thewatch button 111 and the case top heat sink 109.

The insulator spacer 113 may fill in other voids in the assembly aroundone or more of the TEGs 115, the battery 105, and other exposed wires orelectronic components. The insulator spacer 113 may be made from acompressible urethane foam material. The insulator spacer 113 may aid inthe insulation between the case back conductor 119 and the case top heatsink 109. The insulator spacer 113 may also serve to minimize vibrationsor movements in one or more of the TEG wiring, the vibration motorwiring, and the TEG/VIB flexible printed circuit (FPC) 114.

The TEG/VIB FPC 114 may allow the TEGs 115 and vibration motor 116 to beelectrically connected to the main PCB 104.

The one or more TEGs 115 may be solid state devices which convert atemperature gradient between two opposing surfaces into electricalenergy. The two opposing surfaces may be referred to as a “cold side”and a “hot side”. The cold side may be at a lower temperature than thehot side. In the wearable device, the cold side of the TEGs 115 maycomprise a case top heat sink 109. The hot side of the TEGs 115 maycomprise a case back conductor 119.

The vibration motor 116 may provide haptic feedback and usernotifications via vibrations transferred to the case back conductor 119.

The insulator ring 117 may retain the case back and transfer theclamping load from the assembly screws 120 through the case back andinto the TEGs 115. The insulator ring 117 may be made from a low thermalconductivity plastic material. The insulator ring 117 may also separatethe case back conductor 119 from the case top heat sink 109. Theinsulator ring 117 may have a low thermal conductivity, such that theinsulator ring creates a poor heat pathway from the case back conductor119 to the case top heat sink 109. This insulating effect maximizes thetemperature gradient created across the hot and cold sides of the TEGs115.

The one or more cosmetic screws 118 may be made from the same materialand the same screw type as the assembly screws 120. The cosmetic screws118 may be fastened in place through the case back conductor 119. Thecosmetic screws 118 may be added in place to create an aestheticallypleasing circular bolt pattern on the bottom of the watch assembly. Inthe illustrated example, there are four cosmetic screws 118, but othernumbers of cosmetic screws may be used.

The case back conductor 119 may comprise a highly conductive body whichcan be exposed to the user's body (e.g., wrist) on one side and/or indirect contact with the TEGs 115 on the opposing side. The case back maycreate a heat pathway which conducts heat from the user's body to the“hot side” of each of the one or more TEGs 115. Wherever the case backis not in contact with a TEG surface or air, the case back body isinsulated from the case top. The case back conductor 119 may be producedfrom a material with a high coefficient of thermal conductivity such asan aluminum or copper alloy.

The one or more assembly screws 120 may pull the watch enclosuretogether. When threaded into the captive nuts 108, assembly screw headsmay pull the insulator ring 117 against the case back conductor 119,which may, in turn, push the TEGs 115 against the case top heat sink109. The assembly screws 120 ensure the “hot side” and “cold side” ofthe TEGs 115 are pressed against the case back and case top,respectively. In the illustrated example, there are four assembly screws120, but other numbers of assembly screws may be used.

FIG. 2 shows a section view of the wearable device of FIG. 1. Thewearable device may include one or more of a case back conductor 201,one or more thermoelectric generators (TEGs) 202, a case top heat sink203, a battery 204, an insulator ring 205, a watch lens 206, and a mainPCB 207.

During operation of the wearable device, the case back conductor 201 mayefficiently draw body heat from the user's body (e.g, wrist) to the “hotside” (which may be the bottom side) of the TEG 202. The “cold side”(which may be the top side) of the TEG may be connected to the case topheat sink 203, which may efficiently dissipate heat from the TEG to theambient air. The TEG may use this temperature gradient across its “hotside” and “cold side” to generate electrical energy. This electricalenergy may be stored in the battery 204. The insulator ring 205 maycreate a poor heat pathway from the case back conductor to the case topheat sink, thereby maximizing the temperature gradient across the “hotside” and “cold side” of the TEG. The watch lens 206 may hold thewearable device's internal components inside of the case top. The mainPCB 207 may include the electrical components, wiring, and firmwarenecessary for power management, sensing, display, button inputs,diagnostics, and vibration outputs.

FIGS. 3A-3E show various views of the case top heat sink of the wearabledevice of FIG. 1. FIG. 3A is a top view of the case top heat sink of thewearable device. FIG. 3B is a perspective view of the case top heat sinkof the wearable device. FIG. 3C is a right side view of the case topheat sink of the wearable device. FIG. 3D is a front side view of thecase top heat sink of the wearable device. FIG. 3E is a bottom view ofthe case top heat sink of the wearable device. The wearable device'scase top heat sink may include one or more of a cutout 301, a buttonbearing 302, a thermal contact plane 303, a set of ridges and grooves304, and a contact surface 305.

The thermal contact plane 303 (shown in FIG. 3B) may be a material whichsits above the TEGs and which may create a thermal pathway between the“cold side” of the TEGs and the exposed surface area in contact withambient air. The thermal contact plane may contain a cutout 301 (shownin FIG. 3A), which may be a through-hole cutout which allows thickercomponents to be recessed below the thermal contact plane. The contactsurface 305 (shown in FIG. 3E) may be a flat and smooth contact area,which allows for good thermal contact between the case top heat sink andthe “cold-side” of the TEGs. This surface may be coated in a thermallyconductive paste, pad, or epoxy to enhance the quality of the TEGsurface contact. The set of ridges and grooves 304 (shown in FIG. 3D)may comprise features that increase the exposed surface area of thewatch case, thereby increasing the overall heat transfer to ambient air.The button bearing 302 (shown in FIG. 3C) may act as a bearing surfaceand guide for the watch button.

FIGS. 4A-4D show various views of the case back conductor of thewearable device of FIG. 1. FIG. 4A is a top view of the case backconductor of the wearable device. FIG. 4B is a perspective view of thecase back conductor of the wearable device. FIG. 4C are side views ofthe case back conductor of the wearable device. FIG. 4D is a bottom viewof the case back conductor of the wearable device. The case backconductor of the wearable device may include one or more of a TEGcontact surface 401, a vibration motor recess 402, and one or more tabs403.

The TEG contact surface 401 (shown in FIG. 4B) may be a flat and smoothcontact area, which may allow for good thermal contact between the caseback and the “hot side” of the TEGs. This surface may be coated in athermally conductive paste, pad, or epoxy to enhance the quality of theTEG surface contact. The vibration motor recess 402 (shown in FIG. 4A)may be a pocket in which the vibration motor is installed, such that thevibration motor may be placed as close to the wearable device user'sbody (e.g., wrist) as possible. The one or more tabs 403 (shown in FIGS.4C-D) may interface with the insulator ring. The one or more assemblyscrews may be tightened down, causing the case back to clamp the TEGsagainst the case top heat sink. In the illustrated example, there aretwo tabs, but other numbers of tabs may be used.

FIGS. 5A-C show various views of the wearable device of FIG. 1. FIG. 5Ais a top view of the wearable device. FIG. 5B is a left side view of thewearable device. FIG. 5C is a bottom view of the wearable device.

The wearable device may include a watch band 501. The watch band 501 mayensure that the user of the wearable device can comfortably tighten thewatch strap, such that the case back conductor of the wearable device issolidly pressed against their body (e.g., wrist). A tight thermalconnection between the case back conductor and the user's body (e.g.,wrist) may ensure a sufficient temperature gradient in the case backconductor for electrical power generation by the TEGs. The watch bandmay be made from a flexible material, such as silicone or TPE, with aconventional buckle with discrete adjustment points, to allowcomfortable tightening of the watch band.

The watch band 501 may include one or more of a clasp 502 and one ormore straps. The one or more straps may include a top strap 504 and abottom strap 505, which may be wrapped around either side of thewearable device user's body (e.g., wrist) for secure wearing. The topstrap may have a clasp at the end. The bottom strap may have a row ofseveral holes. The clasp may be used to secure the one or more straps ofthe wearable device around the user's body (e.g., wrist). The clasp mayadjust to the size of the user's body for comfortable and securewearing.

FIG. 5A additionally shows the case top heat sink of the wearabledevice. FIG. 5B additionally shows the ridges and grooves of thewearable device. FIG. 5C additionally shows the case back conductor ofthe wearable device.

The wearable device can include at least about 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 50, 100, 500, or 1000 or more thermoelectric generators. Eachthermoelectric generator can include a plurality of thermoelectricelements. Examples of thermoelectric elements are provided elsewhereherein.

The one or more thermoelectric generators of the wearable device canindividually or collectively provide output power of at least about 1microwatts (μW), 10 μW, 100 μW, 1 milliwatt (mW), 10 mW, 20 mW, 30 mW,40 mW, 50 mW, 100 mW, or 1 watt (W), in some cases from 1 μW to 10 mW,at a voltage of at least about 1 millivolt (mV), 2 mV, 3 mV, 4 mV, 5 mV,10 mV, 20 mV, 30 mV, 40 mV, 50 mV, 100 mV, 200 mV, 300 mV, 400 mV, 500mV, 1 volt (V), 2 V, 3 V, 4 V, 5 V or 10 V, in some cases from about 10mV to 10 V. In some situations, a lower voltage can be converted to atleast about 1 V, 2, V, 2.1 V, 2.2 V, 2.3 V, 2.35 V, 2.4 V, 2.45 V, 2.5V, 3 V, 3.1 V, 3.2 V, 3.3 V, 3.4 V, 3.5 V, 3.6 V, 3.7 V, 3.8 V, 3.9 V, 4V, 4.1 V, 4.2 V, 4.3 V, 4.4 V, 4.5 V, or 5.0 V using a DC-DC converterand associated power management circuitry, and can be used to powercircuits directly or to trickle charge a power storage unit such as abattery. An auxiliary power supply, such as a battery, can also beincluded in the apparatus to provide reserve power in times ofintermittent bodily contact, decreased power output or increased powerconsumption.

FIG. 17 shows another example of a wearable device 1700. The wearabledevice includes a top enclosure 1701 and a bottom enclosure 1702. Thetop enclosure 1701 may encase upper TEGs 1711 and serve as the chassisto which an upper body heat conductor plate 1709 and top side heat sink1710 attach. The top enclosure 1701 may be mechanically joined to thespring band 1704. This enclosure may sit across a dorsal or top side ofeither of a user's body (e.g., wrist). Electronics, including elementsof the processing circuitry, sensors, energy harvesting & storagecircuits, user interface elements, or communication systems, may belocated inside this enclosure. The bottom enclosure 1702 may encase thelower TEGs 1712 and serve as the chassis to which the lower body heatconductor plate 1707 and bottom side heat sink 1708 attach. The bottomenclosure 1702 may be mechanically joined to the spring band 1704. Thisenclosure may sit across the palmar or bottom side of either of a user'sbody (e.g., wrist). Like the top enclosure 1701, a variety ofelectronics may also be located and mounted inside this enclosure.

The wearable device 1700 may further include a flexible circuit 1703such as a flexible printed circuit or a flexible-flat cable or similar.The flexible circuit 1703 may electrically connect components in the topenclosure 1701 (e.g., located on the palmar side of the user's wrist) tothose in the bottom enclosure 1702 (e.g., located on the distal side ofthe user's wrist). Additional TEGs, sensors, or circuit elements mayalso be connected to the flexible circuit 1703 at a variety ofpositions, allowing components to be located inside the spring band 1704(i.e., where they may contact the user's body). The spring band 1704 mayserve as the mechanical connection between components in the topenclosure 1701 (e.g., located on the palmar side of the user's wrist) tothose in the bottom enclosure 1702 (e.g., located on the distal side ofthe user's wrist). This leaf-spring like structure may flex open toallow a user to place the device onto their body (e.g., wrist). Thisflexibility may also allow for users of different sizes (e.g., userswith different wrist sizes) to make use of the same product. The springband 1704 and flexible circuit 1703 can also be manufactured indifferent sizes to cover an even larger variation in user size (e.g.,user wrist thickness). The spring band may maintain a slight compressionon the top and bottom sides of the wrist, ensuring that the surfaces ofthe body heat conductor plates 1707 and 1709 are in good thermal contactwith the user's skin. In some situations, the wearable device 1700further includes a battery 1705 that provides energy storage for theelectrical system and a main PCB 1706 which includes the electricalcomponents, wiring, and firmware necessary for power management,sensing, display, user inputs, diagnostics, and interface outputs.

In some situations, the lower body heat conductor plate 1707 includes ahighly conductive body which is exposed to the user's body (e.g., wrist)on one side and in direct contact with the TEGs on the opposing side.The body heat conductor plate may create a heat pathway which conductsheat from the user's body to the “hot-side” of each of the TEGs.Wherever the conductor plate is not in contact with a TEG surface orair, the conductor plate may be insulated from the opposing heat sink1708. The lower body heat conductor plate 1707 may be produced from amaterial with a high coefficient of thermal conductivity such as analuminum or copper alloy. In some situations, the surface that is to bein contact with the user's body (e.g., wrist) may be formed in a domedor contoured shape so as to optimize the thermal contact area betweenthe exposed surface and the user's skin. The upper body heat conductorplate 1709 may allow for a second thermal pathway through an additionalset of TEGs. In some situations, the design of the wearable device 1700can be further segmented, adding additional skin contact points andthermal pathways around the perimeter of the user's body (e.g., wrist).

The bottom side heat sink 1708 may include a highly conductive bodywhich is exposed to the ambient air. A thermal contact plane with asmooth and flat bottom surface may be pressed against the “cold-side” ofthe TEGs (with or without thermal paste in-between). This thermalcontact plane may create a thermal pathway between the TEG “cold-side”and the ambient air. In this configuration, the bottom side heat sink1708 serves to minimize the temperature gradient between the ambient airand the TEG “cold-side”. The top side heat sink 1710 may complete thethermal pathway to ambient air for the TEGs on the top side of theassembly.

FIGS. 18A-18D show various views of the wearable device 1700. FIG. 18Ais a top view of the wearable device. FIG. 18B is a perspective view ofthe wearable device. FIG. 18C is a front view of the wearable device.FIG. 18D is a side view of the wearable device.

FIG. 19A is a cross-sectional side view at section A-A (FIG. 19B) of thewearable device 1700. The wearable device may comprise, as shown in FIG.19A, a top enclosure 1701, a bottom enclosure 1702, a flexible circuit1703, a spring band 1704, a battery 1705, a PCB 1706, bottom and topside heat sinks 1708 & 1710, lower and upper heat conductor plates 1707& 1709 and TEGs 1711 & 1712. The TEGs may be solid state devices whichconvert a temperature gradient between two opposing surfaces intoelectrical energy. Each device may comprise one or more TEGs, forexample, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, or 20 ormore TEGs. The surface area of the heat sink that is exposed to ambientair can be re-sized, reshaped, and further modified to lower the thermalresistance as heat is transferred to the surrounding environment viaconvection and/or radiation. For example, features such as grooves,fins, and pins (FIGS. 20A and 20B) can be used to increase the exposedsurface area and increase convective heat loss, and colored finishes canbe used to maximize radiation. In some cases, the heat sink is made froma solid block, i.e., without heat fins (FIG. 20C).

FIG. 21A is a cross-sectional side view at section B-B (FIG. 21B) andshows another example of a wearable device 2100. The wearable device2100 includes a wearable module 2110, one or more hinge/spring bars2120, a strap enclosure 2130, a flexible circuit 2140, one or more bodyheat conductor nodes 2150, one or more TEGs 2160, and one or moreexternal heat sink nodes 2170.

The wearable module 2110 may take the form of a wristwatch, fitnesstracker, or other device which may serve as a focal point for userinteraction. The wearable module 2110 may house additional electronics,such as processing circuitry, one or more wireless modules, powermanagement circuitry, one or more batteries, one or more displays, oneor more vibration motor, and the like.

The hinge/spring bar 2120 may serve as the attachment point between thestrap enclosure 2130 and the wearable module. In this example, on oneside (right) the strap enclosure is pinned (i.e., free to rotate) arounda spring bar. Further, in this example, the strap enclosure 2130 wrapsaround a second hinge/spring bar to allow a user to don/doff thewearable device 2100 with some degree of adjustability.

The strap enclosure 2130 may serve as the chassis for each conductornode 2150, TEG 2160, and external heat sink node 2170 thermal circuitassembly. The strap enclosure may also encase the flexible circuit 2140or similar wiring which allows each TEG 2160 to be electricallyconnected to one another and the wearable module 2110. The strapenclosure 2130 may serve as the method of donning/doffing the wearabledevice 2100 and may include a clasp or other attachment method whichallows for some degree of adjustability for users of different sizes(e.g., users with different wrist sizes). The strap enclosure 2130 maybe made from a durable but flexible material, such as fabric, leather,TPU, TPE, silicone, or the like. In this example, a “Milanese” loopretention method is employed, where one end of the strap enclosure islooped around a fixed hinge point of the wearable module and doubledback on top of itself. The free end of the strap enclosure can then beheld in place with magnets, Velcro, snaps, or the like (not shown).

The flexible circuit 2140 (which may take the form of a flexible printedcircuit, a flexible-flat cable, or the like) may electrically connectcomponents in the wearable module 2110 (which may be located, forexample, on a dorsal side of a user's wrist) to those in the strapenclosure 2130 (which may be located, for example, on a palmar side of auser's wrist). TEGs, sensors, or circuit elements may be connected tothe flexible circuit 2140 at a variety of positions, allowing componentsto be located adjacent to the user's body (e.g., around thecircumference of the user's wrist). The flexible circuit 2140 mayconnect to the wearable module 2110 through a board-mounted connector, asoldered joint, flying leads, spring pins, contact pads, or the like(not shown).

Each body heat conductor node 2150 may comprise a highly conductive bodywhich can be exposed to the user's body (e.g., wrist) on one side, andin direct contact with a TEG 2160 on the opposing side. A body heatconductor node 2150 may create a heat pathway which can conduct heatfrom the user's body to a “hot-side” of each TEG 2160. Wherever the bodyheat conductor node is not in contact with a TEG surface or air, thebody heat conductor node may be insulated from an opposing external heatsink node 2170. Each body heat conductor node 2150 may be produced froma material with a high coefficient of thermal conductivity, such as analuminum or copper alloy. The surface of each body heat conductor node2150 intended to be in contact with the user's body (e.g., wrist) may beformed in a domed or contoured shape so as to optimize the thermalcontact area and comfort between the exposed surface and the user'sskin. In the illustrated example, there are seven body heat conductornodes 1250 which may contact the user's body (e.g., wrist) at a varietyof positions, but other numbers of body heat conductor nodes may beused.

As described herein, the one or more TEGs 2160 are solid state deviceswhich convert a temperature gradient between two opposing surfaces intoelectrical energy. The two opposing surfaces may be referred to as the“cold-side” and “hot-side”. The one or more TEGs 2160 may be sandwichedbetween one or more body heat conductor nodes 2150 on the “hot-side” andone or more external heat sink nodes 2170 on the “cold-side”. In thisillustrated example, there are seven TEGs 2160 sandwiched between bodyheat conductor nodes 2150 and external heat sink nodes 2170 and locatedat a variety of positions along the strap enclosure 2130 (i.e., locatedat a variety of positions around a perimeter of the user's wrist). Anadvantage of placing the TEG circuits around the perimeter of the user'sbody (e.g., wrist) is that one or more TEGs 2160 can be placed at, forexample, the underside of the wrist, where there is a potential for anelevated skin temperature and thus an increased temperature gradientacross each TEG (i.e., an increased temperature gradient between theuser's skin, a body heat conductor mode, a TEG, an external heat sinknode, and ambient air).

Each external heat sink node 2170 may comprise a highly conductive bodywhich can be exposed to ambient air. Further, each external heat sinknode 2170 may comprise a thermal contact plane with a smooth and flatbottom surface that can be pressed against the “cold-side” of each TEG2160 (with or without thermal paste or other conductive materialin-between). This thermal contact plane may create a thermal pathwaybetween the TEG “cold-side” and the ambient air. In this configuration,each external heat sink node 2170 may serve to minimize the temperaturegradient between the ambient air and the TEG “cold-side”. The surfacearea of each external heat sink node 2170 exposed to ambient air may bere-sized, reshaped, and/or further modified to lower the thermalresistance as heat is transferred to the surrounding environment viaconvection and/or radiation. For example, features such as grooves,fins, and pins may be used to increase the exposed surface area of eachexternal heat sink node 2170 to increase convective heat loss. Further,a variety of finishes may be used to maximize heat transfer from eachexternal heat sink node 2170 to the surrounding environment viaradiation.

FIG. 22 shows a perspective view of the wearable device 2100 of FIG. 21Awithout the strap enclosure 2130. As shown, wearable module 2210 maycomprise a display 2180. The display 2180 may be formed of a materialwhich magnifies an image, such as a lens. The display may be atransparent glass or plastic component which may be adhered to arecessed groove in the top of the wearable module 2210. The display maycover the wearable module 2210 and hold internal components inside ofthe wearable module. Using paint, a decal, silk screen, pad printing orsimilar, a mask may be created to selectively expose or hide certaininternal components. The display 2180 may be an electronic display. Thedisplay 2180 may be a low-power screen which displays a graphical userinterface. The display 2180 may be a capacitive touchscreen or aresistive touchscreen. As an alternative, the display 2180 may be apassive display.

FIG. 23A is a perspective view of the wearable device of FIG. 21A. FIG.23B is a detail view corresponding to detail C of FIG. 23A. An examplearrangement of a body heat conductor node 2150, a TEG 2160, and anexternal heat sink node 2170 are provided in FIG. 23B. As shown and asdescribed herein, body heat conductor node 2150 is located so as to bein contact with a user's skin when wearable device 2100 is donned by auser. For user comfort, body heat conductor node 2150 may compriserounded chamfered edges (as shown), chamfered edges, beveled edges, orany edge configuration that may promote user comfort.

FIG. 24 is an expanded side view of the wearable device of FIG. 21A,showing an example arrangement of a body heat conductor node 2150, a TEG2160, and an external heat sink node 2170 along flexible circuit 2140.

FIG. 25A is a perspective view of the wearable device of FIG. 21A. FIG.25B is a side view of the wearable device of FIG. 21A. As describedherein, body heat conductor nodes 2170 may comprise features such asgrooves, fins (shown), and pins to increase the exposed surface area andincrease convective heat loss.

FIG. 26A is a perspective view of an alternative embodiment of thewearable device of FIG. 21A. FIG. 26B is a side view of an alternativeembodiment of the wearable device of FIG. 21A. As shown in thisalternative embodiment, body heat conductor nodes 2170 may be made froma solid block of conductive material (i.e., without fins).

Methods of Using and Manufacturing Wearable Devices with ThermoelectricModules

Another aspect of the present disclosure provides a method for using awearable electronic device (e.g., watch) with at least onethermoelectric module or unit. The wearable electronic device mayinclude an electronic display with a user interface and a powermanagement unit. The power management unit may be coupled or integratedwith the electronic display. The power management unit may include anenergy storage device and a thermoelectric device in electricalcommunication. The thermoelectric device may include a heat collectingunit, one or more thermoelectric elements, and a heat expelling unit.The heat collecting unit may be in thermal communication with thethermoelectric element. The thermoelectric element may be in thermalcommunication with the heat expelling unit. Using the wearableelectronic device may include activating the wearable electronic device.Using the wearable electronic device may include using thethermoelectric device to generate power. The power may be generated bythe flow of heat from the heat collection unit, across thethermoelectric element, and to the heat expelling unit. The generatedpower may be used to power the electronic display. A portion of thegenerated power may be stored in the energy storage device.

Activating the wearable device may include positioning the heatcollecting unit of the wearable device adjacent to a heat source. Theheat source may be a body surface of the user. Positioning the heatcollecting unit of the wearable device adjacent to a heat source mayinitiate the generation of power. Activating the wearable electronicdevice may include depressing a button to physically activating thewearable device. The button may be a single button or multiple buttons.The buttons may comprise a button spring that physically actuates thebutton. Depressing the button may transfer an input from the user to aPCB board of the wearable electronic device to activate the wearableelectronic device. Activation of the wearable electronic device mayinclude activation of the user interface. The user interface may includea touchscreen. The touchscreen may be a capacitive touch screen. Thetouch screen may be a resistive touch screen. Applying pressure orcontact to the user interface may transfer input from the user to a PCBboard of the wearable electronic device to activate the wearableelectronic device.

The wearable electronic device may include a smart watch, a fitnesstracker, a portable electronic device, or any combination thereof. Inone example, the wearable electronic device is a watch. The watch may besubstantially waterproof or water resistant. In some cases, the watermay be water resistant but not waterproof. The watch may include a userinterface. The user interface may enable the user to access differentfunctionalities of the watch. The user interface may be actuated bybuttons. The user interface may be actuated through use of atouchscreen. The user interface may be actuated by both buttons and theuse of a touch screen. The touchscreen may be a capacitive touch screen.The touch screen may be a resistive touch screen.

The watch may include one or more power generation units in electricalcommunication with the power management unit in addition to thethermoelectric device. The power generation unit may include a solarcell, inductive coupling unit, RF coupling unit, and a kinetic powergeneration unit. The watch may include one or more solar cells. Thesolar cells may be integrated in the body of the watch or the band ofthe watch. The solar cells may generate power during exposure to light.The watch may have at least about 1, 2, 3, 4, 5, 6, 8, 10, 15, 20, ormore solar cells integrated into the body and/or band of the watch. Theinductive coupling unit may be integrated into the power management unitof the watch. The inductive coupling unit may generate powerinductively. The RF coupling unit may be integrated into the powermanagement unit of the watch. The RF coupling unit may generate powerfrom RF waves. The kinetic power generation unit may be integrated intothe power management unit of the watch. The kinetic power generationunit may generate power by motion of the user's body.

FIGS. 27A-27G are illustrations of a wearable electronic device that isa watch. FIG. 27A is a perspective view of an example watch and band.FIG. 27B is a back view an example watch and band. FIG. 27C is a topview of an example watch and band. FIG. 27D is a left side view of anexample watch and band. FIG. 27E is a front view of an example watch andband. FIG. 27F is a right side view of an example watch and band. FIG.27G is a bottom view of an example watch and band. The heat collectingunit of the watch may include the watch back. The watch back may be heldagainst the skin of a user by the watch band. The watch back may collectthe heat of the user and direct the heat into the thermoelectric unit.The casing of the watch may include a case top heat sink. The case topheat sink may be a part of the heat expelling unit. The case top heatsink may draw heat from the thermoelectric element and expel the heatfrom the wearable device. In one example, the case top heat sink maycomprise vents at the top and bottom surface of the wearable device. Insome cases, the wearable device may include at least 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 15, or 20 vents. The one or more vents may have variousshapes and/or sizes. The one or more vents may each be circular,triangular, square, rectangular, or partial shapes or combinationsthereof. The one or more vents may be situated at various locations of abody of the wearable device, such as top, bottom, left side, right side,back side or front side. The one or more vents may permit the flow ofthermal energy to or from an interior portion of the wearable device,which may permit heat transfer.

FIGS. 28A-28C show an alternative embodiment of a wearable electronicdevice that is a watch. FIG. 28A is a view of the face of the watch. Theface of the watch may include a cosmetic dial, fastening screws, lugs,and buttons and knobs. FIG. 28B shows a cross-sectional view the centerof the watch. The center of the watch is defined by the line A-A in FIG.28A. The watch may include a top glass 101, a sealing bezel 2810, a casetop conductor 109, an insulator ring 117, a TEG 115, and a case backconductor 119. FIG. 28C is an exploded view of the components of thewatch. The watch may include a top glass 101, fastening screws 120,glass sealing gasket 2820, sealing bezel 2810, case top heat conductor109, cosmetic dial 2830, electronic display 103, insulator spacer 113,PCB 104, button FPC assembly 2840, insulating ring with lugs 2860,O-ring 2850, TEG 115, and case back conductor 119. The case top may be aone piece case top. The one piece case top may include the case topconductor. The lugs may be attached to the insulator ring. The lugs maynot dissipate heat from the heat expelling unit.

Another aspect of the present disclosure provides a method formanufacturing a wearable electronic device (e.g., watch) with at leastone thermoelectric module or unit. The method may include assembling anelectronic display with a user interface and a power management unit toyield a wearable electronic device. The power management unit may beoperatively coupled with the electronic display. The power managementunit may include an energy storage device and a thermoelectric device inelectrical communication with the energy storage device. Thethermoelectric device may include a heat collecting unit, athermoelectric element, and a heat expelling unit. The heat collectingunit may be in thermal communication with the thermoelectric element.The thermoelectric element may be in thermal communication with the heatexpelling unit. During use of the wearable electronic device thethermoelectric unit may generate power upon flow of thermal energy fromthe heat collecting unit, across the thermoelectric element, and to theheat expelling unit. The generated power may be used to power theelectronic display and user interface. A portion of the power may bestored in the energy storage device.

The wearable electronic device may be a watch. The watch may include acase that contains the electronic display and power management unit. Thecase may be assembled from multiple components. The electronic displaymay be positioned adjacent to the top of the watch case. The top of thewatch case may include a transparent material and the electronic displaymay be visible through the top of the watch case. The components of thewatch may be assembled into the watch case from the top side, the bottomside, or both sides.

FIGS. 29A-29C show an example watch that is assembled from the top sideof the case. FIG. 29A is a view of the face of the watch. The face ofthe watch may include a cosmetic dial, fastening screws, lugs, andbuttons and knobs. FIG. 29B shows a cross-sectional view of the centerof the watch. The center of the watch is defined by the line A-A in FIG.29A. The top surface of the watch may include a top glass 101 and asealing bezel 2810. The center portion of the watch may include a casetop heat conductor 109. The bottom portion of the watch, which may bethe portion in contact with a body surface of the user, may include aninsulator ring 117, one or more TEGs 115, and a case back conductor 119.FIG. 29C is an exploded view of the components of an example watchassembled from the top side of the case. The components may include topglass 101, glass sealing gasket 2820, fastening screws 120, sealingbezel 2810, O-rings 2850, cosmetic dial 2830, electronics and displaysubassembly 2910, flexible printed circuit 114, case top conductor 109,O-ring 2850, Insulator ring with lugs 2860, TEG 115, and case backconductor 119. The case back conductor 119 may collect heat from a bodysurface of a user. The heat may be directed across the TEG 115 to theheat expelling unit. The heat expelling unit may be the case topconductor 109. The case top conductor 109 may include conductive fins toincrease heat dissipation. Alternatively, or in addition to, the casetop conductor 109 may include vents to increase heat dissipation. Thelugs may be positioned on the insulator ring 2860. The lugs may not aidin the dissipation of heat. The case may be sealed at the top side andthe bottom side. The case may be sealed at the top side by a sealinggasket 2820 and sealing bezel 2810. The sealed case may allow for thewatch to be resistant to damage from water and other liquids. The sealedcase may be substantially waterproof or water resistant. In some cases,the sealed case may be water resistant but not waterproof.

FIGS. 30A-30C show an alternative example watch that is assembled fromthe top side of the case. FIG. 30A is a view of the face of the watch.The face of the watch may include a cosmetic dial, fastening screws,lugs, and buttons and knobs. FIG. 30B shows a cross-sectional view ofthe center of the watch. The center of the watch is defined by the lineA-A in FIG. 30A. The top surface of the watch may include a top glass101 and a sealing bezel 2810. The center portion of the watch mayinclude a case top heat conductor 109. The bottom portion of the watch,which may be the portion in contact with a body surface of the user, mayinclude an insulator ring 117, one or more TEGs 115, and a case backconductor 119. FIG. 30C is an exploded view of the components of analternative example watch assembled from the top side of the case. Thecomponents may include top glass 101, glass sealing gasket 2820,fastening screws 120, sealing bezel 2810, O-rings 2850, cosmetic dial2830, electronics and display subassembly 2910, flexible printed circuit114, case top conductor with lugs 3010, insulator ring 117, and caseback conductor 119. The case back conductor 119 may collect heat from abody surface of a user. The heat may be directed across the TEG 115 tothe heat expelling unit. The heat expelling unit may be the case topconductor 3010. The case top conductor 3010 may include conductive finsand lugs to increase heat dissipation. Alternatively, or in addition to,the case top conductor 3010 may include vents to increase heatdissipation. The lugs may aid in the dissipation of heat. The case maybe sealed at the top side and the bottom side. The case may be sealed atthe top side by a sealing gasket 2820 and sealing bezel 2810. The sealedcase may allow for the watch to be resistant to damage from water andother liquids. The sealed case may be substantially waterproof or waterresistant.

FIGS. 31A-31C show an example watch that is assembled from the bottomside of the case. FIG. 31A is a view of the face of the watch. The faceof the watch may include a cosmetic dial, cosmetic screws, lugs, andbuttons and knobs. FIG. 31B shows a cross-sectional view of the centerof the watch. The center of the watch is defined by the line A-A in FIG.31A. The top surface of the watch may include a top glass 101 and thecenter portion of the watch may include a case top heat conductor 109.The bottom portion of the watch, which may be the portion in contactwith a body surface of the user, may include heat spreader plate 3110,one or more TEGs 115, and a case back conductor 119. FIG. 31C is anexploded view of the components of an example watch assembled from thebottom side of the case. The components may include top glass 101, glasssealing gasket 2820, cosmetic screws 118, electronics and displaysubassembly 2910, flexible printed circuit 114, case top conductor 109,heat spreader plate 3110, fastener screws 120, O-rings 2850, insulatorring with lugs 2860, TEG 115, and case back conductor 119. The case backconductor 119 may collect heat from a body surface of a user. The heatmay be directed across the TEG 115 to the heat expelling unit. The heatexpelling unit may be the case top conductor 109. The case top conductor109 may include conductive fins to increase heat dissipation.Alternatively, or in addition to, the case top conductor 109 may includevents to increase heat dissipation. The lugs may be positioned on theinsulator ring 2860. The lugs may not aid in the dissipation of heat.The case may be sealed at the top side and the bottom side. The case maybe sealed at the bottom side with an O-ring 2850 and fastener screws120. A watch assembled from the bottom side may enable the watch to bemore resistant to damage from water and liquids than a watch assembledfrom the top side. The sealed case may be substantially waterproof orwater resistant.

FIGS. 32A-32E show an alternative example watch that is assembled fromthe bottom side of the case and includes a separate threaded in bottomsubassembly. FIG. 32A is a view of the face of the watch. The face ofthe watch may include a cosmetic dial, cosmetic screws, lugs, andbuttons and knobs. FIG. 32B shows a cross-sectional view of the centerof the watch. The center of the watch is defined by the line A-A in FIG.32A. The top surface of the watch may include a top glass 101 and thecenter portion of the watch may include a threaded case top conductor3210. The bottom portion of the watch, which may be the portion incontact with a body surface of the user, may include a threaded heatspreader plate 3220, an insulator ring with lugs 2860, one or more TEGs115, and a case back conductor 119. FIG. 32C is an exploded view of thecomponents of an alternative example watch assembled from the bottomside of the case. The components may include top glass 101, glasssealing gasket 2820, cosmetic screws 118, threaded case top conductor3210, cosmetic dial 2830, electronics and display subassembly 2910,insulator ring with lugs 2860, and threaded case bottom subassembly3230. The threaded case bottom subassembly 3230 may comprise the heatcollecting unit and the thermoelectric element. The insulating ring 2860may comprise the lugs. The lugs may not aid to dissipate heat.

FIG. 32D is an exploded view of an electronic and display subassembly2910 for a watch assembled from the bottom side of the case. Thecomponents may include a main PCB 104, FPC 114, display retainer 102,electronic display 103, and light guide 3320.

FIG. 32E is an exploded view of an example threaded case bottomsubassembly 3230 for a watch assembled from the bottom side of the case.The components may include fastener screws 120, flexible printed circuit114, insulator spacer 113, threaded heat spreader plate 3210, TEG 115,O-rings 2850, insulator ring 117, and case back conductor 119. Thethreaded case bottom subassembly 3230 may mate with the threads from thethreaded case top conductor 3210. The threads from the threaded casebottom subassembly 3230 may aid in the dissipation of heat. Threadingthe threaded case bottom subassembly 3230 into the threaded case topconductor 3210 may seal the watch. The watch may be resistant to damagefrom water and other liquids. The watch may be substantially waterproofor water resistant.

FIGS. 33A-33E show an alternative example watch that is assembled fromthe bottom side of the case and includes a separate snap-in bottomsubassembly. FIG. 33A is a view of the face of the watch. The face ofthe watch may include a cosmetic dial, cosmetic screws, lugs, andbuttons and knobs. FIG. 33B shows a cross-sectional view of the centerof the watch. The center of the watch is defined by the line A-A in FIG.33A. The top surface of the watch may include a top glass 101 and thecenter portion of the watch may include a snap-in case top conductor3310. The bottom portion of the watch, which may be the portion incontact with a body surface of the user, may include a snap in heatspreader plate with lugs 3320, an insulator ring 117, one or more TEGs115, and a case back conductor 119. FIG. 33C is an exploded view of thecomponents of an alternative example watch assembled from the bottomside of the case. The components may include cosmetic screws 118, topglass 101, glass sealing gasket 2820, snap-in case top conductor 3310,cosmetic dial 2830, electronics and display subassembly 2910, O-rings2850, and snap-in case bottom subassembly 3330. The snap-in case bottomsubassembly 3330 may comprise the heat collecting unit and thethermoelectric element. The snap-in case bottom subassembly 3330 mayadditionally comprise lugs. The lugs may aid in dissipating heat.

FIG. 32D is an exploded view of an electronic and display subassembly2910 for a watch assembled from the bottom side of the case. Thecomponents may include a main PCB 104, FPC 114, display retainer 102,electronic display 103, and light guide 3320.

FIG. 32E is an exploded view of an example snap-in case bottomsubassembly 3330 for a watch assembled from the bottom side of the case.The components may include fastener screws 120, flexible printed circuit114, insulator spacer 113, snap-in heat spreader plate 3310, TEG 115,O-rings 2850, insulator ring 117, and case back conductor 119. Thesnap-in case bottom subassembly may mate with corresponding features inthe snap-in case top conductor 3310. Snapping the snap-in case bottomsubassembly 3330 into the snap-in case top conductor 3310 may seal thewatch. The watch may be resistant to damage from water and otherliquids. The watch may be substantially waterproof or water resistant.

Thermoelectric Elements, Devices and Systems

The present disclosure provides thermoelectric elements, devices andsystems that can be employed for use in various applications, such asheating and/or cooling applications, power generation, consumerapplications and industrial applications. Such thermoelectric elementsmay be used with wearable devices of the present disclosure, such aswatches. In some examples, thermoelectric materials are used in consumerelectronic devices (e.g., smart watches, portable electronic devices,and health/fitness tracking devices). As another example, athermoelectric material of the present disclosure can be used in anindustrial setting, such as at a location where there is heat loss. Insuch a case, heat can be captured by a thermoelectric device and used togenerate power.

Thermoelectric devices of the present disclosure can be used to generatepower upon the application of a temperature gradient across suchdevices. Such power can be used to provide electrical energy to varioustypes of devices, such as consumer electronic devices.

Thermoelectric devices of the present disclosure can have variousnon-limiting advantages and benefits. In some cases, thermoelectricdevices can have substantially high aspect ratios, uniformity of holesor wires, and figure-of-merit, ZT, which can be suitable for optimumthermoelectric device performance. With respect to the figure-of-merit,Z can be an indicator of coefficient-of-performance (COP) and theefficiency of a thermoelectric device, and T can be an averagetemperature of the hot and the cold sides of the thermoelectric device.In some embodiments, the figure-of-merit (ZT) of a thermoelectricelement or thermoelectric device is at least about 0.01, 0.02, 0.03,0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35,0.4, 0.45 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0,1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4,2.5, 2.6, 2.7, 2.8, 2.9, or 3.0 at 25° C. In some case, thefigure-of-merit is from about 0.01 to 3, 0.1 to 2.5, 0.5 to 2.0 or 0.5to 1.5 at 25° C.

The figure of merit (ZT) can be a function of temperature. In somecases, ZT increases with temperature. For example, a thermoelectrichaving a ZT of 0.5 at 25° C. can have a greater ZT at 100° C.

Thermoelectric devices of the present disclosure can have electrodeseach comprising an array of nanostructures (e.g., holes or wires). Thearray of nanostructures can include a plurality of holes or elongatestructures, such as wires (e.g., nanowires). The holes or wires can beordered and have uniform sizes and distributions. As an alternative, theholes or wires may not be ordered and may not have a uniformdistribution. In some examples, there is no long range order withrespect to the holes or wires. In some cases, the holes or wires mayintersect each other in random directions. Methods for forming patternedor disordered patterns of nanostructures (e.g., holes or wires) areprovided elsewhere herein.

The present disclosure provides thermoelectric elements that areflexible or substantially flexible. A flexible material can be amaterial that can be conformed to a shape, twisted, or bent withoutexperiencing plastic deformation. This can enable thermoelectricelements to be used in various settings, such as settings in whichcontact area with a heat source or heat sink is important. For example,a flexible thermoelectric element can be brought in efficient contactwith a heat source or heat sink, such as by wrapping the thermoelectricelement around the heat source or heat sink.

A thermoelectric device can include one or more thermoelectric elements.The thermoelectric elements can be flexible. An individualthermoelectric element can include at least one semiconductor substratewhich can be flexible. In some cases, individual semiconductorsubstrates of a thermoelectric element are rigid but substantially thin(e.g., 500 nm to 1 mm or 1 micrometer to 0.5 mm) such that they providea flexible thermoelectric element when disposed adjacent one another.Similarly, individual thermoelectric elements of a thermoelectric devicecan be rigid but substantially thin such that they provide a flexiblethermoelectric device when disposed adjacent one another.

FIG. 6 shows a thermoelectric device 600, in accordance with someembodiments of the present disclosure. The thermoelectric device 600includes n-type 601 and p-type 602 elements disposed between a first setof electrodes 603 and a second set of electrodes 604 of thethermoelectric device 600. The first set of electrodes 603 connectsadjacent n-type 601 and p-type elements, as illustrated.

The electrodes 603 and 604 are in contact with a hot side material 605and a cold side material 606 respectively. In some embodiments, the hotside material 605 and cold side material 606 are electrically insulatingbut thermally conductive. The application of an electrical potential tothe electrodes 603 and 604 leads to the flow of current, which generatesa temperature gradient (ΔT) across the thermoelectric device 600. Thetemperature gradient (ΔT) extends from a first temperature (average),T1, at the hot side material 605 to a second temperature (average), T2,at the cold side material 606, where T1>T2. The temperature gradient canbe used for heating and cooling purposes.

The n-type 601 and p-type 602 elements of the thermoelectric device 600can be formed of structures having dimensions from nanometers tomicrometers, such as, e.g., nanostructures. In some situations, thenanostructures are holes or inclusions, which can be provided in anarray of holes (i.e., mesh). In other situations, the nanostructures arerod-like structures, such as nanowires. In some cases, the rod-likestructures are laterally separated from one another.

In some cases, the n-type 601 and/or p-type 602 elements are formed ofan array of wires or holes oriented along the direction of thetemperature gradient. The wires may extend from the first set ofelectrodes 603 to the second set of electrodes 604. In other cases, then-type 601 and/or p-type 602 elements are formed of an array of holesoriented along a direction that is angled between about 0° and 90° inrelation to the temperature gradient. In an example, the array of holesis orthogonal to the temperature gradient. The holes or wires, in somecases, have dimensions on the order of nanometers to micrometers. Insome cases, holes can define a nanomesh.

FIG. 7 is a schematic perspective view of a thermoelectric element 700having an array of holes 701 (select holes circled), in accordance withan embodiment of the present disclosure. The array of holes can bereferred to as a “nanomesh” herein. FIGS. 8 and 9 are perspective topand side views of the thermoelectric element 700. The element 700 can bean n-type or p-type element, as described elsewhere herein. The array ofholes 701 includes individual holes 701 a that can have widths fromseveral nanometers or less up to microns, millimeters or more. In someembodiments, the holes have widths (or diameters, if circular) (“d”)between about 1 nm and 500 nm, or 5 nm and 100 nm, or 10 nm and 30 nm.The holes can have lengths (“L”) from about several nanometers or lessup to microns, millimeters or more. In some embodiments, the holes havelengths between about 0.5 microns and 1 centimeter, or 1 micron and 500millimeters, or 10 microns and 1 millimeter.

The holes 701 a are formed in a substrate 700 a. In some cases, thesubstrate 700 a is a solid state material, such as e.g., carbon (e.g.,graphite or graphene), silicon, germanium, gallium arsenide, aluminumgallium arsenide, silicides, silicon germanium, bismuth telluride, leadtelluride, oxides (e.g., SiO_(x), where ‘x’ is a number greater thanzero), gallium nitride and tellurium silver germanium antimony (TAGS)containing alloys. For example, the substrate 700 a can be a Group IVmaterial (e.g., silicon or germanium) or a Group III-V material (e.g.,gallium arsenide). The substrate 700 a may be formed of a semiconductormaterial comprising one or more semiconductors. The semiconductormaterial can be doped n-type or p-type for n-type or p-type elements,respectively.

In some cases, the holes 701 a are filled with a gas, such as He, Ne,Ar, N₂, H₂, CO₂, O₂, or a combination thereof. In other cases, the holes701 a are under vacuum. Alternatively, the holes may be filled (e.g.,partially filled or completely filled) with a semiconductor material, aninsulating (or dielectric) material, or a gas (e.g., He, Ar, H₂, N₂,CO₂).

A first end 702 and second end 703 of the element 700 can be in contactwith a substrate having a semiconductor-containing material, such assilicon or a silicide. The substrate can aid in providing an electricalcontact to an electrode on each end 702 and 703. Alternatively, thesubstrate can be precluded, and the first end 702 and second end 703 canbe in contact with a first electrode (not shown) and a second electrode(not shown), respectively.

In some embodiments, the holes 701 a are substantially monodisperse.Monodisperse holes may have substantially the same size, shape and/ordistribution (e.g., cross-sectional distribution). In other embodiments,the holes 701 a are distributed in domains of holes of various sizes,such that the holes 701 a are not necessarily monodisperse. For example,the holes 701 a may be polydisperse. Polydisperse holes can have shapes,sizes and/or orientations that deviate from one another by at leastabout 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 30%, 40%, or 50%.In some situations, the device 700 includes a first set of holes with afirst diameter and a second set of holes with a second diameter. Thefirst diameter is larger than the second diameter. In other cases, thedevice 700 includes two or more sets of holes with different diameters.

The holes 701 a can have various packing arrangements. In some cases,the holes 701 a, when viewed from the top (see FIG. 8), have a hexagonalclose-packing arrangement.

In some embodiments, the holes 701 a in the array of holes 701 have acenter-to-center spacing between about 1 nm and 500 nm, or 5 nm and 100nm, or 10 nm and 30 nm. In some cases, the center-to-center spacing isthe same, which may be the case for monodisperse holes 701 a. In othercases, the center-to-center spacing can be different for groups of holeswith various diameters and/or arrangements.

The dimensions (lengths, widths) and packing arrangement of the holes701, and the material and doping configuration (e.g., dopingconcentration) of the element 700 can be selected to effect apredetermined electrical conductivity and thermal conductivity of theelement 700, and a thermoelectric device having the element 700. Forinstance, the diameters and packing configuration of the holes 701 canbe selected to minimize the thermal conductivity, and the dopingconcentration can be selected to maximize the electrical conductivity ofthe element 700.

The doping concentration of the substrate 700 a can be at least about10¹⁸ cm⁻³, 10¹⁹ cm⁻³, 10²⁰ cm⁻³, or 10²¹ cm⁻³. In some examples, thedoping concentration is from about 10¹⁸ to 10²¹ cm⁻³, or 10¹⁹ to 10²⁰cm⁻³. The doping concentration can be selected to provide a resistivitythat is suitable for use as a thermoelectric element. The resistivity ofthe substrate 700 a can be at least about 0.001 ohm-cm, 0.01 ohm-cm, or0.1 ohm-cm, and in some cases less than or equal to about 1 ohm-cm, 0.5ohm-cm, 0.1 ohm-cm. In some examples, the resistivity of the substrate700 a is from about 0.001 ohm-cm to 1 ohm-cm, 0.001 ohm-cm to 0.5ohm-cm, or 0.001 ohm-cm to 0.1 ohm-cm.

The array of holes 701 can have an aspect ratio (e.g., the length of theelement 700 divided by width of an individual hole 701 a) of at leastabout 1.5:1, or 2:1, or 5:1, or 10:1, or 20:1, or 50:1, or 100:1, or1000:1, or 5,000:1, or 10,000:1, or 100,000:1, or 1,000,000:1, or10,000,000:1, or 100,000,000:1, or more.

The holes 701 can be ordered and have uniform sizes and distributions.As an alternative, the holes 701 may not be ordered and may not have auniform distribution. For example, the holes 701 can be disordered suchthat there is no long range order for the pattern of holes 701.

In some embodiments, thermoelectric elements can include an array ofwires. The array of wires can include individual wires that are, forexample, rod-like structures.

As an alternative to the array of holes of the element 700, the holesmay not be ordered and may not have a uniform distribution. In someexamples, there is no long range order with respect to the holes. Insome cases, the holes may intersect each other in random directions. Theholes may include intersecting holes, such as secondary holes thatproject from the holes in various directions. The secondary holes mayhave additional secondary holes. The holes may have various sizes andmay be aligned along various directions, which may be random and notuniform.

FIG. 10 is a schematic perspective top view of a thermoelectric element1000, in accordance with an embodiment of the present disclosure. FIG.11 is a schematic perspective top view of the thermoelectric element1000. The thermoelectric element 1000 may be used with devices, systemsand methods provided herein. The element 1000 includes an array of wires1001 having individual wires 1001 a. In some embodiments, the wires havewidths (or diameters, if circular) (“d”) between about 1 nm and 500 nm,or 5 nm and 100 nm, or 10 nm and 30 nm. The wires can have lengths (“L”)from about several nanometers or less up to microns, millimeters ormore. In some embodiments, the wires have lengths between about 0.5microns and 1 centimeter, or 1 micron and 500 millimeters, or 10 micronsand 1 millimeter.

In some embodiments, the wires 1001 a are substantially monodisperse.Monodisperse wires may have substantially the same size, shape and/ordistribution (e.g., cross-sectional distribution). In other embodiments,the wires 1001 a are distributed in domains of wires of various sizes,such that the wires 1001 a are not necessarily monodisperse. Forexample, the wires 1001 a may be polydisperse. Polydisperse wires canhave shapes, sizes and/or orientations that deviate from one another byat least about 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 30%, 40%,or 50%.

In some embodiments, the wires 1001 a in the array of wires 1001 have acenter-to-center spacing between about 1 nm and 500 nm, or 5 nm and 100nm, or 10 nm and 30 nm. In some cases, the center-to-center spacing isthe same, which may be the case for monodisperse wires 1001. In othercases, the center-to-center spacing can be different for groups of wireswith various diameters and/or arrangements.

In some embodiments, the wires 1001 a are formed of a solid statematerial, such as a semiconductor material, such as, e.g., silicon,germanium, gallium arsenide, aluminum gallium arsenide, silicide alloys,alloys of silicon germanium, bismuth telluride, lead telluride, oxides(e.g., SiO_(x), where ‘x’ is a number greater than zero), galliumnitride and tellurium silver germanium antimony (TAGS) containingalloys. The wires 1001 a can be formed of other materials disclosedherein. The wires 1001 a can be doped with an n-type dopant or a p-typedopant. The doping concentration of the semiconductor material can be atleast about 10¹⁸ cm⁻³, 10¹⁹ cm⁻³, 10²⁰ cm⁻³, or 10²¹ cm⁻³. In someexamples, the doping concentration is from about 10¹⁸ to 10²¹ cm⁻³, or10¹⁹ to 10²⁰ cm⁻³. The doping concentration of the semiconductormaterial can be selected to provide a resistivity that is suitable foruse as a thermoelectric element. The resistivity of the semiconductormaterial can be at least about 0.001 ohm-cm, 0.01 ohm-cm, or 0.1 ohm-cm,and in some cases less than or equal to about 1 ohm-cm, 0.5 ohm-cm, 0.1ohm-cm. In some examples, the resistivity of the semiconductor materialis from about 0.001 ohm-cm to 1 ohm-cm, 0.001 ohm-cm to 0.5 ohm-cm, or0.001 ohm-cm to 0.1 ohm-cm.

In some embodiments, the wires 1001 a are attached to semiconductorsubstrates at a first end 1002 and second end 1003 of the element 1000.The semiconductor substrates can have the n-type or p-type dopingconfiguration of the individual wires 1001 a. In other embodiments, thewires 1001 a at the first end 1002 and second end 1003 are not attachedto semiconductor substrates, but can be attached to electrodes. Forinstance, a first electrode (not shown) can be in electrical contactwith the first end 1002 and a second electrode can be electrical contactwith the second end 1003.

With reference to FIG. 11, space 1004 between the wires 1001 a may befilled with a vacuum or various materials. In some embodiments, thewires are laterally separated from one another by an electricallyinsulating material, such as a silicon dioxide, germanium dioxide,gallium arsenic oxide, spin on glass, and other insulators depositedusing, for example, vapor phase deposition, such as chemical vapordeposition or atomic layer deposition. In other embodiments, the wiresare laterally separated from one another by vacuum or a gas, such as He,Ne, Ar, N₂, H₂, CO₂, O₂, or a combination thereof.

The array of wires 1001 can have an aspect ratio—length of the element1000 divided by width of an individual wire 1001 a—of at least about1.5:1, or 2:1, or 5:1, or 10:1, or 20:1, or 50:1, or 100:1, or 1000:1,or 5,000:1, or 10,000:1, or 100,000:1, or 1,000,000:1, or 10,000,000:1,or 100,000,000:1, or more. In some cases, the length of the element 1000and the length of an individual wire 1001 a are substantially the same.

Thermoelectric elements provided herein can be incorporated inthermoelectric devices for use in cooling and/or heating and, in somecases, power generation. In some examples, the device 600 may be used asa power generation device. In an example, the device 600 is used forpower generation by providing a temperature gradient across theelectrodes and the thermoelectric elements of the device 600.

As an alternative to the array of wires of the element 1000, the wiresmay not be ordered and may not have a uniform distribution. In someexamples, there is no long range order with respect to the wires. Insome cases, the wires may intersect each other in random directions. Thewires may have various sizes and may be aligned along variousdirections, which may be random and not uniform.

FIG. 12 shows a thermoelectric device 1200 having n-type elements 1201and p-type elements 1202, in accordance with an embodiment of thepresent disclosure. The n-type elements 1201 and p-type elements 1202each include an array of wires, such as nanowires. An array of wires caninclude a plurality of wires. The n-type elements 1201 include n-type(or n-doped) wires and the p-type elements 1202 include p-type wires.The wires can be nanowires or other rod-like structures.

Adjacent n-type elements 1201 and p-type elements 1202 are electricallyconnected to one another at their ends using electrodes 1203 and 1204.The device 1200 includes a first thermally conductive, electricallyinsulating layer 1205 and a second thermally conductive, electricallyinsulating layer 1206 at opposite ends of the elements 1201 and 1202.

The device 1200 includes terminals 1207 and 1208 that are in electricalcommunication with the electrodes 1203 and 1204. The application of anelectrical potential across the terminals 1207 and 1208 generates a flowof electrons and holes in the n-type and p-type elements 1201 and 1202,respectively, which generates a temperature gradient across the elements1201 and 1202. The first thermally conductive, electrically insulatinglayer 1205 is a cold side of the device 1200; the second thermallyconductive, electrically insulating layer 1206 is a hot side of thedevice 1200. The cold side is cooler (i.e., has a lower operatingtemperature) than the hot side.

FIG. 13 shows a thermoelectric device 1300 having n-type elements 1301and p-type elements 1302, in accordance with an embodiment of thepresent disclosure. The n-type elements 1301 and p-type elements 1302are formed in n-type and p-type semiconductor substrates, respectively.Each substrate can include an array of holes, such as nanoholes. Thearray of holes can include a plurality of holes. An individual hole canspan the length of an n-type or p-type element. The holes can bemonodisperse, in which case hole dimensions and center-to-center spacingmay be substantially constant. In some cases, the array of holesincludes holes with center-to-center spacing and hole dimensions (e.g.,widths or diameters) that may be different. In such a case, the holesmay not be monodisperse.

Select n-type elements 1301 and p-type elements 1302 are electricallyconnected to one another at their ends by electrodes 1303 and 1304. Thedevice 1300 includes a first thermally conductive, electricallyinsulating layer (“first layer”) 1305 and a second thermally conductive,electrically insulating layer (“second layer”) 1306 at opposite ends ofthe elements 1301 and 1302.

The device 1300 includes terminals 1307 and 1308 that are in electricalcommunication with the electrodes 1303 and 1304. The application of anelectrical potential across the terminals 1307 and 1308 generates theflow of electrons and holes in the n-type and p-type elements 1301 and1302, respectively, which generates a temperature gradient across theelements 1301 and 1302. The first thermally conductive, electricallyinsulating layer 1305 is a cold side of the device 1300; the secondthermally conductive, electrically insulating layer 1306 is a hot sideof the device 1300. The cold side is cooler (i.e., has a lower operatingtemperature) than the hot side.

The thermoelectric device 1300 has a temperature gradient from thesecond thermally conductive, electrically insulating layer 1306 to thefirst thermally conductive, electrically insulating layer 1305. In somecases, the holes are disposed parallel to a vector oriented from thefirst layer 1305 to the second layer 1306. In other cases, the holes aredisposed at an angle greater than 0° in relation to the vector. Forinstance, the holes can be disposed at an angle of at least about 1°,10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, or 90° in relation to thevector.

FIG. 14 shows a thermoelectric device 1400 having n-type elements 1401and p-type elements 1402, with the elements having holes formed insubstrates of the n-type and p-type elements. The holes are orientedperpendicular to a vector (“V”) orthogonal to the electrodes 1403 and1404 of the device 1400.

Wires or holes of thermoelectric elements provided herein may be formedin a substrate and oriented substantially anti-parallel to a supportstructure, such as an electrode. In some examples, the wires or holesare oriented at an angle greater than 0°, or 10°, or 20°, or 30°, or40°, or 50°, or 60°, or 70°, or 80°, or 85° in relation to the supportstructure. In an example, the wires or holes are oriented at an angle ofabout 90° in relation to the support structure. The electrode may be anelectrode of a thermoelectric device. In some cases, wires or holes maybe oriented substantially parallel to the electrode.

As an alternative to the devices of FIGS. 12-14, a thermoelectric devicecan have a thermoelectric element with an array of holes or wires withindividual holes or wires that may have different sizes and/ordistributions. An array of holes or wires may not be ordered and may nothave a uniform distribution. In some examples, there is no long rangeorder with respect to the holes or wires. In some cases, the holes orwires may intersect each other in random directions. The holes or wiresmay include intersecting holes or wires, such as secondary holes orwires that project from other holes or wires in various directions. Theholes or wires may have various sizes and may be aligned along variousdirections, which may be random and not uniform. As another alternative,a thermoelectric device can include at least one thermoelectric element(p or n-type) with an order array of holes or wires, and at least onethermoelectric element (p or n-type) with a disordered array of holes orwires. The disordered array of holes or wires may include holes or wiresthat are not ordered and do not have a uniform distribution.

A hole or wire of the disclosure may have a surface roughness that issuitable for optimized thermoelectric device performance. In some cases,the root mean square roughness of a hole or wire is between about 0.1 nmand 50 nm, or 1 nm and 20 nm, or 1 nm and 10 nm. The roughness can bedetermined by transmission electron microscopy (TEM) or other surfaceanalytical technique, such as atomic force microscopy (AFM) or scanningtunneling microscopy (STM). The surface roughness may be characterizedby a surface corrugation.

Methods for Forming Thermoelectric Elements

The present disclosure provides various methods for formingthermoelectric elements. A thermoelectric element can be formed usingelectrochemical etching. In some cases, a thermoelectric element isformed by cathodic or anodic etching, in some cases without the use of acatalyst. A thermoelectric element can be formed without use of ametallic catalysis. A thermoelectric element can be formed withoutproviding a metallic coating on a surface of a substrate to be etched.This can also be performed using purely electrochemical anodic etchingand suitable etch solutions and electrolytes. As an alternative, athermoelectric can be formed using metal catalyzed electrochemicaletching in suitable etch solutions and electrolytes, as described in,for example, PCT/US2012/047021, filed Jul. 17, 2012, PCT/US2013/021900,filed Jan. 17, 2013, PCT/US2013/055462, filed Aug. 16, 2013,PCT/US2013/067346, filed Oct. 29, 2013, each of which is entirelyincorporated herein by reference.

Recognized herein are various benefits to not using catalysts to formthermoelectric elements. In an example, a non-metal catalyzed etch canpreclude the need for metal (or metallic) catalysts, which can providefor fewer processing steps, including cleanup steps to remove the metalcatalysts from the thermoelectric element after etching. This can alsoprovide for reduced manufacturing cost, as metal catalysts can beexpensive. Metal catalysts can include rare and/or expensive metallicmaterials (e.g., gold, silver, platinum, or palladium), and eliminatingthe use of a metallic catalyst can advantageously decrease the cost offorming thermoelectric elements. Additionally, the non-catalyzed processcan be more reproducible and controllable. In some cases, thenon-catalyzed process described herein can be scaled from a relativelysmall production scale of thermoelectric elements to a relatively largerproduction scale of thermoelectric elements.

The present disclosure provides methods for forming thermoelectricmaterials for use in various applications, such as consumer andindustrial applications. In some examples, thermoelectric materials areused in consumer electronic devices (e.g., smart watches, portableelectronic devices, and health/fitness tracking devices). As anotherexample, a thermoelectric material of the present disclosure can be usedin an industrial setting, such as at a location where there is heatloss, which heat can be captured and used to generate power.

The present disclosure provides methods for forming flexible orsubstantially flexible thermoelectric materials. A flexible material canbe a material that bends at an angle of least about 1°, 5°, 10°, 15°,20°, 25°, 30°, 35°, 40°, 45°, 50°, 60°, 70°, 80°, 90°, 100°, 120°, 130°,140°, 150°, 160°, 170°, or 180° relative to a measurement plane withoutexperiencing plastic deformation or breaking. The flexible material canbend under an applied force over a given area of the flexible material(i.e., pressure). Plastic deformation can be measured by, for example,three-point testing (e.g., instron extension) or tensile testing. As analternative or in addition to, the flexible material can be a materialthat bends at an angle of least about 1°, 5°, 10°, 15°, 20°, 25°, 30°,35°, 40°, 45°, 50°, 60°, 70°, 80°, 90°, 100°, 120°, 130°, 140°, 150°,160°, 170°, or 180° relative to a measurement plane at a plasticdeformation that is less than or equal to about 20%, 15%, 10%, 5%, 1%,or 0.1% as measured by three-point testing (e.g., instron extension) ortensile testing. A flexible material can be a substantially pliablematerial. A flexible material can be a material that can conform or moldto a surface. Such materials can be employed for use in varioussettings, such as consumer and industrial settings. Thermoelectricelements formed according to methods herein can be formed into variousshapes and configurations. Such shapes can be changed as desired by auser, such as to conform to a given object. The thermoelectric elementscan have a first shape, and after being formed into a shape orconfiguration the thermoelectric elements can have a second shape. Thethermoelectric elements can be transformed from the second shape to theinitial shape.

In an aspect of the present disclosure, a thermoelectric device (ormaterial) is formed using anodic etching. Anodic etching can beperformed in an electrochemical etch cell that provides electricalconnections to the substrate being etched, one or more reservoirs tohold the etch solutions or electrolytes in contact with the substrate,and access for analytical measurements or monitoring of the etchingprocess. The etch solutions and/or electrolytes can comprise an aqueoussolution. The etch (or etching) solutions and/or electrolytes can be abasic, neutral, or acidic solution. Examples of etching solutionsinclude acids, such as hydrofluoric acid (HF), hydrochloric acid (HCl),hydrogen bromide (HBr), hydrogen iodide (HI), or combinations thereof.The etch solutions and/or electrolytes can be an electrically conductivesolution. In an example, the etch cell includes a top reservoir thatcontains a solution comprising an electrolyte. The top reservoir can besituated adjacent to (e.g., on top of) a substrate to be etched. Thesubstrate to be etched can be substantially free of one or more metallicmaterial, which may be catalytic materials. The substrate to be etchedmay be free of a metallic coating. In some examples, the substrate to beetched has a metal content (e.g., on a surface of the substrate) that isless than about 25%, 20%, 15%, 10%, 5%, 1%, 0.1%, 0.01%, 0.001%,0.0001%, 0.00001%, or 000001%, as measured by x-ray photoelectronspectroscopy (XPS).

An etching solution can include an acid (e.g., HF) or a concentration ofacids (taken as a weight percentage) that is less than or equal to about70%, 60%, 50%, 40%, 30%, 20% or 10% (by weight), in some cases greaterthan or equal to about 1%, 10%, 20%, or 30%. In some examples, theconcentration (by weight) is from about 1% to 60%, or 10% to 50%, or 20%to 45%. The balance of the etching solution can include a solvent (e.g.,water) and an additive, such as an alcohol, carboxylic acid, ketoneand/or aldehyde. In some examples, the additive is an alcohol, such asmethanol, ethanol, isopropanol, or a combination thereof. The additivecan enable the user of lower current densities while formingnanostructures (e.g., holes) with properties that are suitable for usein thermoelectric elements of the present disclosure, such as asubstantially uniform distribution of holes having a disordered pattern.The additive can enable the user of lower current densities whileforming nanostructures (e.g., holes) with properties that are suitablefor use in thermoelectric elements of the present disclosure, such asincreased control of the spacing between two or more holes. The additivecan enable the user of lower current densities while formingnanostructures (e.g., holes) with properties that are suitable for usein thermoelectric elements of the present disclosure, such as spacingbetween two or more holes of at most about 5 nm. The additive can enablethe use of lower current densities while forming nanostructures (e.g.,holes) with properties that are suitable for use in thermoelectricelements of the present disclosure, such as spacing between two or moreholes of at most about 20 nm. The additive can enable the use of lowercurrent densities while forming nanostructures (e.g., holes) withproperties that are suitable for use in thermoelectric elements of thepresent disclosure, such as spacing between two or more holes of at mostabout 100 nm.

Electric current can be sourced to and/or through the substrate using anedge or backside contact, through the solution/electrolyte, and into acounter electrode. The counter electrode can be in electricalcommunication with the top reservoir, in some cases situated in the topreservoir. In some cases, the counter electrode is adjacent to or incontact with a top side of the substrate. The body of the etch cell canbe fabricated from materials inert to the etch solution or electrolyte(e.g., PTFE, PFA, polypropylene, HDPE). The edge or backside contact caninclude a metal contact on the substrate, or it can be a liquid contactusing a suitable electrolyte. The counter electrode can include a wireor mesh constructed from a suitable electrode material. The etch cellcan contain mechanical paddles or ultrasonic agitators to maintainsolution motion, or the entire cell may be spun, rotated or shaken. Insome examples, agitating the solution before and/or during etching canprovide for improved etching uniformity. This can enable the electrolyteto be circulated during etching. In another example, the etch cell cancontain one or more recirculating reservoirs and etch chambers, with oneor more solutions/electrolytes.

In an example, an unpatterned substrate is loaded into reaction spaceprovided with up to five or more electrode connections. One of theelectrodes is in ohmic contact with the substrate backside (the workingelectrode) and is isolated from an etchant electrolyte. One of theelectrodes can be in ohmic contact with the substrate backside (theworking electrode) and may not be in contact with an etchantelectrolyte. Another electrode (the counter electrode) can be submergedin the electrolyte but not in direct contact with the substrate, andused to supply current through the electrolyte to the substrate workingelectrode. Another electrode (the reference electrode) is immersed inthe electrolyte and isolated from both the working and counterelectrodes, in some cases using a frit, and used to sense the operatingpotential of the etch cell using a known or predetermined referencestandard. Another two or more electrodes may be placed outside thereaction space in order to set up an external electric field. In somecases, at least two electrodes—a working electrode and a counterelectrode—are required.

The reaction space can be used in a number of ways. In one approach, thereaction space can be used in a two-electrode configuration by passingan anodic current via the substrate backside through a suitableelectrolyte. The electrolyte can be, for example, a liquid mixturecontaining a diluent, such as water, or a fluoride-containing reagent,such as hydrofluoric acid, or an oxidizer, such as hydrogen peroxide.The electrolyte can include surfactants and/or modifying agents. Theworking potential can be sensed during anodization using the counterelectrode in a three-electrode configuration. The anodization can beperformed in the presence of a DC or AC external field using theelectrodes placed outside the reaction space.

In anodic etching, a voltage/current assisted etch of a semiconductorcan result in etching of the semiconductor at a rate dependent on thevoltage/current. The etch rate, etch depth, etch morphology, poredensity, pore structure, internal surface area and surface roughness canbe controlled by the voltage/current, etch solution/electrolytecomposition and other additives, pressure/temperature, front/backsideillumination, and stirring/agitation. They can also be controlled by thecrystal orientation, dopant type, resistivity (doping concentration),and growth process (e.g., float-zone or Czochralski) of thesemiconductor. The resistivity of the semiconductor can be at leastabout 0.001 ohm-cm, 0.01 ohm-cm, or 0.1 ohm-cm, and in some cases lessthan or equal to about 1 ohm-cm, 0.5 ohm-cm, 0.1 ohm-cm. In someexamples, the resistivity of the semiconductor is from about 0.001ohm-cm to 1 ohm-cm, 0.001 ohm-cm to 0.5 ohm-cm, or 0.001 ohm-cm to 0.1ohm-cm.

During etching of a semiconductor substrate using voltage/currentcontrol, a potential or bias (e.g., direct current bias) is applied tothe substrate using an underlying electrode. This can result in thesemiconductor substrate being etched. As a result of anodic etching, thesemiconductor's thermal conductivity can drop significantly. In someexamples, by employing an applied bias, the porosity (mass loss) can becontrolled and tuned and therefore the thermal and electrical propertiescan be controlled. In other examples, by employing a specific etchsolution/electrolyte composition and/or additives the porosity can becontrolled. In yet other examples, by employing any number of variablesalready listed, the porosity can be controlled.

In some cases, the semiconductor substrate is unpatterned and in somecases it is patterned. In an unpatterned etch, the substrate is etcheddirectly in the cell. In a patterned etch, a blocking layer thatprevents etching can first be placed over the semiconductor, and thenremoved in specific locations. This layer may be formed in any mannersuitable (e.g., chemical vapor deposition, spin-coating, oxidation) andthen be removed in a subsequent step in desired locations (e.g., plasmaetching, reactive ion etching, sputtering) using a suitable mask (e.g.,photolithography). Alternatively, a blocking layer can be depositeddirectly (e.g., dip pen lithography, inkjet printing, spray coatingthrough a stencil). Subsequently, a negative replica of the pattern inthe blocking layer is transferred into the substrate during the anodicetch.

The etch can be performed by applying an electrical potential(“potential”) to the semiconductor substrate, in the presence of asuitable etch solution/electrolyte. The potential can be, for example,at least about +0.01 V, +0.02 V, +0.03 V, +0.04 V, +0.05 V, +0.06 V,+0.07 V, +0.08 V, +0.09 V, +0.1 V, +0.2 V, +0.3 V, +0.4 V, +0.5 V, +0.6V, +0.7 V, +0.8 V, +0.9 V, +1.0 V, +2.0 V, +3.0 V, +4.0 V, +5.0 V, +10V, +20 V, +30 V, +40 V, or +50 V relative to a reference, such asground. In some examples, the potential is from about +0.01 V to +20 V,+0.1 V to +10 V, or +0.5 V to +5 V relative to a reference. In someexamples, the potential can range from about +0.01 V to +0.05 V, +0.06 Vto +0.1 V, +0.2 V to +0.5 V, +0.6 V to +1.0 V, +2.0 V to +5.0 V, +10 Vto +20 V, +20V to +30 V, +30V to +40 V, or +40V to +50. In someexamples, the potential is from about +0.5 V to +5 V or from about +1 Vto +5 V.

The etch can be performed by applying or generating an electricalcurrent (“current”) to or through the semiconductor substrate, in somecases in the presence of a suitable etch solution/electrolyte. Thecurrent can be applied to the substrate upon the application of thepotential to the substrate. The current can have a current density, forexample, of at least about +0.01 milliamps per square centimeter(mA/cm²), +0.1 mA/cm², +0.2 mA/cm², +0.3 mA/cm², +0.4 mA/cm², +0.5mA/cm², +0.6 mA/cm², +0.7 mA/cm², +0.8 mA/cm², +0.9 mA/cm², +1.0 mA/cm²,+2.0 mA/cm², +3.0 mA/cm², +4.0 mA/cm², +5.0 mA/cm², +6.0 mA/cm², +7.0mA/cm², +8.0 mA/cm², +9.0 mA/cm², +10 mA/cm², +20 mA/cm², +30 mA/cm²,+40 mA/cm², +50 mA/cm², +60 mA/cm², +70 mA/cm², +80 mA/cm², +90 mA/cm²,+100 mA/cm², +200 mA/cm², +300 mA/cm², +400 mA/cm², +500 mA/cm², +600mA/cm², +700 mA/cm², +800 mA/cm², +900 mA/cm², +1000 mA/cm², or more. Insome examples, the current density ranges from about 0.01 mA/cm² to 20mA/cm², 0.05 mA/cm² to 10 mA/cm², or 0.01 mA/cm² to 5 mA/cm². In someexamples, the current density ranges from about +0.1 mA/cm² to +0.5mA/cm², +0.6 to +1.0 mA/cm², +1.0 mA/cm² to +5.0 mA/cm², +5.0 mA/cm² to+10 mA/cm², +10 mA/cm² to +20 mA/cm², +20 mA/cm² to +30 mA/cm², +30mA/cm² to +40 mA/cm², +40 mA/cm² to +50 mA/cm², +50 mA/cm² to +60mA/cm², +60 mA/cm² to +70 mA/cm², +70 mA/cm² to +80 mA/cm², +80 mA/cm²to +90 mA/cm², +90 mA/cm² to +100 mA/cm², +10 mA/cm² to +200 mA/cm², +20mA/cm² to +300 mA/cm², +300 mA/cm² to +400 mA/cm², +40 mA/cm² to +500mA/cm², +500 mA/cm² to +600 mA/cm², +600 mA/cm² to +700 mA/cm², +700mA/cm² to +800 mA/cm², +800 mA/cm² to +900 mA/cm², or +900 mA/cm² to+1000 mA/cm². In some examples, the current density is from about 1mA/cm² to 30 mA/cm², 5 mA/cm² to 25 mA/cm², or 10 mA/cm² to 20 mA/cm².Such current densities may be achieved with potential provided herein,such as a potential from about +0.5 V to +5 V or from about +1 V to +5V.

The electrical potential (or voltage) can be measured using a voltmeter,for instance. The voltmeter can be in parallel with the substrate. Forexample, the voltmeter can be measure the electrical potential betweentwo sides of the substrate, or the electrical potential between aworking electrode and counter electrode in solution. The current densitycan be measured using an ammeter. The ammeter can be in series with apower source and the substrate. For example, the ammeter can be coupledto a backside of the substrate.

Thermoelectric elements of the present disclosure can be formed at anetching time that is selected to provide an array of nanostructures(e.g., holes or wires). Etching times can range from 1 second to 2 days,1 minute to 1 day, 1 minute to 12 hours, 10 minutes to 6 hours, or 30minutes to 3 hours. In some examples, the etching time is from 30minutes to 6 hours, or 1 hour to 6 hours. In some cases, etching timescan be at least about 1 second, 10 seconds, 30 seconds, 1 minute, 2minutes, 3 minutes, 4 minutes, 5 minutes, 10 minutes, 30 minutes, 1hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 12 hours, 1 day, ormore. Such etching times can be used in combination with applied voltageand/or current of the present disclosure.

In some cases, the bias applied to the semiconductor substrate can bechanged during etching to regulate the etch rate, etch depth, etchmorphology, pore density, pore structure, internal surface area andsurface roughness of the semiconductor substrate, including the densityand location of nanostructuring in the semiconductor substrate. Inanother case, the etch solution/electrolyte composition and/or additivescan be changed during etching. In yet other cases, thepressure/temperature or illumination or stirring/agitation can bechanged. Alternatively, more than one of these variables may be changedsimultaneously to obtain the desired etch characteristics.

During the period in which the substrate is etched, the electricalpotential can be constant, varied or pulsed. In an example, theelectrical potential is constant during the etching period. In anotherexample, the electrical potential is pulsed on and off, or from positiveto negative, during the etching period. In another example, theelectrical potential is varied during the etching period, such as variedgradually from a first value to a second value, which second value canbe less than or greater than the first value. The electrical potentialcan then be varied from the second value to the first value, and so on.In yet another example, the bias/current may be oscillated according toa sinusoidal/triangular/arbitrary waveform. In some cases, thebias/current can be pulsed with a frequency of at least about 1 Hz, 10Hz, 1000 Hz, 5000 Hz, 10000 Hz, 50000 Hz, or 100000 Hz.

The bias and/or current can be DC or AC, or a combination of DC and AC.Use of an AC bias and/or current with DC offset can provide control overthe etch rate using the DC bias/current and control over ions using theAC bias/current. The AC bias/current can alternately enhance and retardthe etch rate, or increase/decrease the porosity/surface roughness, ormodify the morphology and structure in a periodic or non-periodicfashion. The amplitude and frequency of the AC bias/current can be usedto tune the etch rate, etch depth, etch morphology, pore density, porestructure, internal surface area and surface roughness.

In some situations, the application of an electrical potential to asemiconductor substrate during etching can provide for a given etchrate. In some examples, the substrate can be etched at a rate of atleast about 0.1 nanometers (nm)/second (s), 0.5 nm/s, 1 nm/s, 2 nm/s, 3nm/s, 4 nm/s, 5 nm/s, 6 nm/s, 7 nm/s, 8 nm/s, 9 nm/s, 10 nm/s, 20 nm/s,30 nm/s, 40 nm/s, 50 nm/s, 60 nm/s, 70 nm/s, 80 nm/s, 90 nm/s, 100 nm/s,200 nm/s, 300 nm/s, 400 nm/s, 500 nm/s, 600 nm/s, 700 nm/s, 800 nm/s,900 nm/s, 1000 nm/s, or 10,000 nm/s at 25° C. In other cases, the etchrate may be increased/decreased with a change in pressure/temperature,solution/electrolyte composition and/or additives, illumination,stirring/agitation.

The porosity of a semiconductor substrate during etching using anapplied potential or current density can provide a substrate with aporosity (mass loss) that can provide a thermoelectric element that issuitable for various applications. In some examples, the porosity is atleast about 0.01%, 0.1%, 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, or more.The porosity can be from about 0.01% to 99.99%, 0.1% to 60%, or 1% to50%.

A substrate can have a thickness that is selected to yield athermoelectric element that is suitable for various applications. Thethickness can be at least about 100 nanometers (nm), 500 nm, 1micrometer (micron), 5 microns, 10 microns, 100 microns, 500 microns, 1millimeter (mm), or 10 mm. In some examples, the thickness is from about500 nm to 1 mm, 1 micron to 0.5 mm, or 10 microns to 0.5 mm.

The etch may be performed to completion through the entire thickness ofthe substrate, or it may be stopped at any depth. A complete etch yieldsa self-supporting nanostructured material with no underlying unetchedsubstrate. An incomplete etch yields a layer of nanostructured materialover underlying unetched substrate. The nanostructured layer may have athickness at least about 10 nanometers (nm), 20 nm, 30 nm, 40 nm, 50 nm,60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600nm, 700 nm, 800 nm, 900 nm, 1 micrometers (μm), 2 μm, 3 μm, 4 μm, 5 μm,6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm,80 μm, 90 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm,800 μm, 900 μm, 1 millimeters (mm), 2 millimeters (mm), 3 millimeters(mm), 4 millimeters (mm), 5 millimeters (mm), 6 millimeters (mm), 7millimeters (mm), 8 millimeters (mm), 9 millimeters (mm), 10 millimeters(mm), or more.

The nanostructured layer may be left on the substrate, or it may beseparated from the substrate in a number of ways. The layer may bemechanically separated from the substrate (e.g., using a diamond saw,scribing and cleaving, laser cutting, peeling off). Alternatively, thelayer can be separated from the substrate by effecting electropolishingconditions at the etching front at the base of the layer. Theseconditions can be achieved by a change in pressure, change intemperature, change in solution composition, change in electrolytecomposition, use of additives, illumination, stirring, and/or agitation,or by waiting a sufficient duration of time (e.g., more than about 1day). In some cases, a partial or incomplete separation may be desired,such that the layer is still weakly attached to the substrate. This canbe achieved by varying between normal etching conditions andelectropolishing. Complete separation can then be achieved in asubsequent step.

After etching, the material may be chemically modified to yieldfunctionally active or passive surfaces. For example, the material maybe modified to yield chemically passive surfaces, or electronicallypassive surfaces, or biologically passive surfaces, or thermally stablesurfaces, or a combination of the above. This can be accomplished usinga variety of methods, e.g., thermal oxidation, thermal silanation,thermal carbonization, hydrosilylation, Grignard reagents,electrografting. In some cases, one or more of the above methods may beused to obtain a surface with the desired or otherwise predeterminedcombination of properties.

After modification, the voids in the material may also be fully orpartially impregnated with a filling material. For example, the fillingmaterial may be electrically conductive, or thermally insulating, ormechanically strengthening, or a combination of the above. Suitablefilling materials may include one or more of the following groups:insulators, semiconductors, semimetals, metals, polymers, gases, orvacuum. Filling can be accomplished using a variety of methods, e.g.,atomic layer deposition, chemical vapor deposition, deposition fromchemical bath or polymerization bath, electrochemical deposition, dropcasting or spin coating or immersion followed by evaporation of asolvated filling material. In some cases, one or more of the abovemethods may be used to obtain filling materials with the desiredcombination of properties.

After filling, the material may also be sealed with a capping material.For example, the capping material may be impermeable to gases, orliquids, or both. Suitable filling materials may include one or more ofthe following groups: insulators, semiconductors, semimetals, metals orpolymers. Capping can be accomplished using a variety of methods, e.g.,atomic layer deposition, chemical vapor deposition, deposition fromchemical bath or polymerization bath, electrochemical deposition, dropcasting or spin coating or immersion followed by evaporation of asolvated filling material. In some cases, one or more of the abovemethods may be used to obtain capping materials with the desired orpredetermined combination of properties.

After etching, the material can be washed with a suitable rinsingsolution (e.g., water, methanol, ethanol, isopropanol, toluene, hexanesetc.) and dried (e.g., blow drying, evaporative drying, oven/furnacedrying, vacuum drying, critical point drying, or air drying). Therinsing solution can be selected depending on the mode of drying.

After anodic etching, the thermal and electrical properties of thesemiconductor may be further controlled or tuned by coarsening orannealing the semiconductor nanostructure (pore or hole morphology,density, structure, internal surface area and surface roughness) throughthe application of heat and time. Temperatures between about 50° C. and1500° C., or 100° C. and 1300° C. for a time period from about 1 secondto 1 week can be utilized to control the thermal and electricalproperties of the semiconductor. In some cases, the time period is atleast about 1 second, 10 seconds, 30 seconds, 1 minute, 2 minutes, 3minutes, 4 minutes, 5 minutes, 10 minutes, 30 minutes, 1 hour, 2 hours,3 hours, 4 hours, 5 hours, 6 hours, 12 hours, 1 day, or more. Theannealing may be performed in vacuum (e.g., at a pressure that is fromabout 1×10⁻¹⁰ Torr to less than 760 Torr) or in the presence of asuitable gas (e.g., helium, neon, argon, xenon, hydrogen, nitrogen,forming gas, carbon monoxide, carbon dioxide, oxygen, water vapor, air,methane, ethane, propane, sulfur hexafluoride and mixtures thereof). Thegas can be an inert gas. Annealing can be performed on partially orcompletely etched substrates, completely separated etched layers onunetched substrates, partially separated etched layers on unetchedsubstrates, or unseparated etched layers on unetched substrates. In somecases, when layers on unetched substrates are annealed, thesemiconductor coarsening may proceed in such a fashion as to separatethe layers from the unetched substrate. This can be convenient foreffecting layer separation.

Electrical contacts may be deposited on or adjacent to thenanostructured material using standard deposition techniques (e.g.,silk-screening, inkjet deposition, painting, spraying, dip-coating,soldering, metal sputtering, metal evaporation). The electrical contactsmay be metal contacts (e.g., gold, silver, copper, aluminum, indium,gallium, lead-containing solder, lead-free solder or combinationsthereof) with/without suitable adhesion layers (e.g., titanium,chromium, nickel or combinations thereof). Alternatively, the electricalcontacts may be silicide contacts (e.g., titanium silicide, cobaltsilicide, nickel silicide, palladium silicide, platinum silicide,tungsten silicide, molybdenum silicide etc.). Barrier layers (e.g.,platinum, palladium, tungsten nitride, titanium nitride, molybdenumnitride etc.) may be inserted to prevent inter-diffusion between thesilicon and the contact, or between contact layers, or between everylayer. In other examples, the electrical contacts may be combinations ofboth metal and silicide contacts. A silicide contact can be provided toreduce contact resistance between a metal contact and the substrate.Examples of silicides include tungsten silicide, titanium disilicide andnickel silicide. A subsequent annealing step may be used to form thecontact and improve its properties. For example annealing can reducecontact resistance, which can provide an ohmic contact.

After electrical contacts have been formed, the material can beassembled into a thermoelectric device comprising of p- and n-typethermoelectric elements (or legs). A thermoelectric device can includep- and n-legs connected electrically in series, and thermally inparallel with each other. The thermoelectric device can be built uponelectrically insulating and thermally conductive rigid plates (e.g.,aluminum nitride, aluminum oxide, silicon carbide, silicon nitride etc.)with electrical connections between the legs provided by metalinterconnects (e.g., copper, aluminum, gold, silver etc.). In anotherexample, the thermoelectric material may be assembled on a flexibleinsulating material (e.g., polyimide, polyethylene, polycarbonate etc.).Electrical connections between the legs are provided via metalinterconnects integrated on the flexible material. The resultingthermoelectric may be in sheet, roll or tape form. Desired sizes ofthermoelectric material may be cut out from the sheet, roll or tape andassembled into devices.

Processing conditions (e.g., applied voltages and current densities)provided herein have various unexpected benefits, such as the formationof nanostructures (e.g., holes) having orientations and configurationsthat provide thermoelectric elements and devices of the presentdisclosure with enhanced or otherwise improved properties, such as athermoelectric element with a ZT from about 0.01 to 3, 0.1 to 2.5, 0.5to 2.0 or 0.5 to 1.5 at 25° C. Such processing conditions can providefor the formation of an array of nanostructures in a substrate. Thearray of nanostructures can have a disordered pattern. Such processingconditions can provide for the formation of flexible thermoelectricelements or devices.

FIG. 15 schematically illustrates a method for manufacturing a flexiblethermoelectric device comprising a plurality of thermoelectric elements.A p-type or n-type silicon substrate that has been processed using, forexample, a non-catalytic approach described elsewhere herein (e.g.,anodic etching) is coated on both sides with a suitable contactmaterial, such as titanium, nickel, chromium, tungsten, aluminum, gold,platinum, palladium, or any combination thereof. The substrate is thenheated to a temperature of at least about 250° C., 300° C., 350° C.,400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., 750° C.,800° C., 850° C., 900° C., 950° C., or 1000° C., and cut into multiplepieces using, for example, a diamond cutter, wire saw, or laser cutter.

Next, in a metallization operation, individual pieces of the cutsubstrate are placed on bottom and top tapes having widths of about 30centimeters (cm). The tapes can be formed of a polymeric material, suchas, for example, polyimide, polycarbonate, polyethylene, polypropylene,or copolymers, mixtures and composites of these and other polymers.

Next, the individual pieces are subjected to solder coating to formserial connections to the individual pieces across a given tape. Thetapes are then combined through one or more rollers (two rollers areillustrated). A thermally conductive adhesive can be provided around thetables to help seal the individual pieces between the tapes.

Thermoelectric elements, devices and systems formed according to methodsprovided herein can have various physical characteristics. Theperformance of a thermoelectric device of the disclosure may be relatedto the properties and characteristics of holes and/or wires ofthermoelectric elements. In some cases, optimum device performance maybe achieved for an element having holes or wires, an individual hole orwire having a surface roughness between about 0.1 nm and 50 nm, or 1 nmand 20 nm, or 1 nm and 10 nm, as measured by transmission electronmicroscopy (TEM). In some cases, a thermoelectric element may have aresidual metal content that is less than or equal to about 0.000001%,0.00001%, 0.0001%, 0.001%, 0.01%, 0.1%, 1%, 5%, 10%, 15%, 20%, or 25%,as measured by x-ray photoelectron spectroscopy (XPS).

A thermoelectric element of the present disclosure may have a surfaceroughness that is suitable for optimized thermoelectric deviceperformance. In some cases, the root mean square roughness of a hole orwire is between about 0.1 nm and 50 nm, or 1 nm and 20 nm, or 1 nm and10 nm. The roughness can be determined by transmission electronmicroscopy (TEM) or other surface analytical technique, such as atomicforce microscopy (AFM) or scanning tunneling microscopy (STM). Thesurface roughness may be characterized by a surface corrugation.

Thermoelectric elements, devices and systems of the present disclosurecan be employed for use in various settings or employed for varioususes. Settings can include, without limitation, healthcare, consumer,and industrial settings. Such uses include, without limitation, flexiblethermoelectric tape with flexible heat sinks, wearable electronicdevices powered by body heat, waste heat recovery units for generatingpower (e.g., waste heat recovery unit in a vehicle or chemical plant).

Heat sink can aid in collecting or dissipating heat. A heat sink caninclude one or more heat fins which can be sized and arranged to provideincrease heat transfer area.

Computer Control Systems

The present disclosure provides computer control systems that areprogrammed or otherwise configured to implement various devices, methodsand systems of the present disclosure. FIG. 16 shows a computer system(also “system” herein) 1601 programmed or otherwise configured tofacilitate the formation of thermoelectric devices of the presentdisclosure. The system 1601 can be programmed or otherwise configured toimplement methods described herein. The system 1601 includes a centralprocessing unit (CPU, also “processor” and “computer processor” herein)1605, which can be a single core or multi core processor, or a pluralityof processors for parallel processing. The system 1601 also includesmemory 1610 (e.g., random-access memory, read-only memory, flashmemory), electronic storage unit 1615 (e.g., hard disk), communicationsinterface 1620 (e.g., network adapter) for communicating with one ormore other systems, and peripheral devices 1625, such as cache, othermemory, data storage and/or electronic display adapters. The memory1610, storage unit 1615, interface 1620 and peripheral devices 1625 arein communication with the CPU 1605 through a communications bus (solidlines), such as a motherboard. The storage unit 1615 can be a datastorage unit (or data repository) for storing data. The system 1601 isoperatively coupled to a computer network (“network”) 1630 with the aidof the communications interface 1620. The network 1630 can be theInternet, an internet and/or extranet, or an intranet and/or extranetthat is in communication with the Internet. The network 1630 in somecases is a telecommunication and/or data network. The network 1630 caninclude one or more computer servers, which can enable distributedcomputing, such as cloud computing. The network 1630 in some cases, withthe aid of the system 1601, can implement a peer-to-peer network, whichmay enable devices coupled to the system 1601 to behave as a client or aserver.

The system 1601 is in communication with a processing system 1635 forforming thermoelectric elements and devices of the disclosure. Theprocessing system 1635 can be configured to implement various operationsto form thermoelectric devices provided herein, such as formingthermoelectric elements and forming thermoelectric devices (e.g.,thermoelectric tape) from the thermoelectric elements. The processingsystem 1635 can be in communication with the system 1601 through thenetwork 1630, or by direct (e.g., wired, wireless) connection. In anexample, the processing system 1635 is an electrochemical etchingsystem. In another example, the processing system 1635 is a dry box.

The processing system 1635 can include a reaction space for forming athermoelectric element from the substrate 1640. The reaction space canbe filled with an electrolyte and include electrodes for etching (e.g.,cathodic or anodic etching).

Methods as described herein can be implemented by way of machine (orcomputer processor) executable code (or software) stored on anelectronic storage location of the system 1601, such as, for example, onthe memory 1610 or electronic storage unit 1615. During use, the codecan be executed by the processor 1605. In some examples, the code can beretrieved from the storage unit 1615 and stored on the memory 1610 forready access by the processor 1605. In some situations, the electronicstorage unit 1615 can be precluded, and machine-executable instructionsare stored on memory 1610.

The code can be pre-compiled and configured for use with a machine havea processer adapted to execute the code, or can be compiled duringruntime. The code can be supplied in a programming language that can beselected to enable the code to execute in a pre-compiled or as-compiledfashion.

Aspects of the systems and methods provided herein, such as the system1601, can be embodied in programming. Various aspects of the technologymay be thought of as “products” or “articles of manufacture” typicallyin the form of machine (or processor) executable code and/or associateddata that is carried on or embodied in a type of machine readablemedium. Machine-executable code can be stored on an electronic storageunit, such memory (e.g., read-only memory, random-access memory, flashmemory) or a hard disk. “Storage” type media can include any or all ofthe tangible memory of the computers, processors or the like, orassociated modules thereof, such as various semiconductor memories, tapedrives, disk drives and the like, which may provide non-transitorystorage at any time for the software programming. All or portions of thesoftware may at times be communicated through the Internet or variousother telecommunication networks. Such communications, for example, mayenable loading of the software from one computer or processor intoanother, for example, from a management server or host computer into thecomputer platform of an application server. Thus, another type of mediathat may bear the software elements includes optical, electrical andelectromagnetic waves, such as used across physical interfaces betweenlocal devices, through wired and optical landline networks and overvarious air-links. The physical elements that carry such waves, such aswired or wireless links, optical links or the like, also may beconsidered as media bearing the software. As used herein, unlessrestricted to non-transitory, tangible “storage” media, terms such ascomputer or machine “readable medium” refer to any medium thatparticipates in providing instructions to a processor for execution.

Hence, a machine readable medium, such as computer-executable code, maytake many forms, including but not limited to, a tangible storagemedium, a carrier wave medium or physical transmission medium.Non-volatile storage media include, for example, optical or magneticdisks, such as any of the storage devices in any computer(s) or thelike, such as may be used to implement the databases, etc. shown in thedrawings. Volatile storage media include dynamic memory, such as mainmemory of such a computer platform. Tangible transmission media includecoaxial cables; copper wire and fiber optics, including the wires thatcomprise a bus within a computer system. Carrier-wave transmission mediamay take the form of electric or electromagnetic signals, or acoustic orlight waves such as those generated during radio frequency (RF) andinfrared (IR) data communications. Common forms of computer-readablemedia therefore include for example: a floppy disk, a flexible disk,hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD orDVD-ROM, any other optical medium, punch cards paper tape, any otherphysical storage medium with patterns of holes, a RAM, a ROM, a PROM andEPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wavetransporting data or instructions, cables or links transporting such acarrier wave, or any other medium from which a computer may readprogramming code and/or data. Many of these forms of computer readablemedia may be involved in carrying one or more sequences of one or moreinstructions to a processor for execution.

Methods described herein can be automated with the aid of computersystems having storage locations with machine-executable codeimplementing the methods provided herein, and a processor for executingthe machine-executable code.

Devices, systems and methods provided herein may be combined with ormodified by other devices, systems and methods, such as devices, systemsand/or methods described in U.S. Pat. No. 7,309,830 to Zhang et al.,U.S. Patent Publication No. 2006/0032526 to Fukutani et al. U.S. PatentPublication No. 2009/0020148 to Boukai et al., U.S. Patent PublicationNo. 2013/0019918 to Boukai et al., U.S. Patent Publication No.2015/0280099, U.S. Patent Publication No. 2016/0197259,PCT/US2012/047021, filed Jul. 17, 2012, PCT/US2013/021900, filed Jan.17, 2013, PCT/US2013/055462, filed Aug. 25, 2013, PCT/US2013/067346,filed Oct. 29, 2013, and PCT/US16/64501, filed Dec. 1, 2016, each ofwhich is entirely incorporated herein by reference.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. It is not intendedthat the invention be limited by the specific examples provided withinthe specification. While the invention has been described with referenceto the aforementioned specification, the descriptions and illustrationsof the embodiments herein are not meant to be construed in a limitingsense. Numerous variations, changes, and substitutions will now occur tothose skilled in the art without departing from the invention.Furthermore, it shall be understood that all aspects of the inventionare not limited to the specific depictions, configurations or relativeproportions set forth herein which depend upon a variety of conditionsand variables. It should be understood that various alternatives to theembodiments of the invention described herein may be employed inpracticing the invention. It is therefore contemplated that theinvention shall also cover any such alternatives, modifications,variations or equivalents. It is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

What is claimed is:
 1. A wearable electronic device, comprising: anelectronic display with a user interface for displaying information to auser; and a power management unit operatively coupled with saidelectronic display, wherein said power management unit comprises anenergy storage device and at least one thermoelectric device inelectrical communication with said energy storage device, wherein saidthermoelectric device comprises (i) a heat collecting unit that restsadjacent to a body surface of said user, which heat collecting unitcollects thermal energy from said body surface of said user, (ii) athermoelectric element in thermal communication with said heatcollecting unit, and (iii) a heat expelling unit in thermalcommunication with said thermoelectric element, which heat expellingunit expels thermal energy from said thermoelectric element, wherein,during use, said thermoelectric element generates power upon flow ofthermal energy from said heat collecting unit, across saidthermoelectric element and to said heat expelling unit, wherein at leasta portion of said power is stored in said energy storage device.
 2. Thewearable electronic device of claim 1, wherein said wearable electronicdevice is integrated with said power management unit.
 3. The wearableelectronic device of claim 1, wherein said power management unitprovides at least about 10% of a power requirement of said wearableelectronic device.
 4. The wearable electronic device of claim 1, whereinsaid power management unit provides at least about 20% of a powerrequirement of said wearable electronic device.
 5. The wearableelectronic device of claim 1, wherein said power management unitprovides at least about 30% of a power requirement of said wearableelectronic device.
 6. The wearable electronic device of claim 1, whereinsaid power management unit provides at least about 40% of a powerrequirement of said wearable electronic device.
 7. The wearableelectronic device of claim 1, wherein said power management unitprovides at least about 60% of a power requirement of said wearableelectronic device.
 8. The wearable electronic device of claim 1, whereinsaid power management unit provides at least about 80% of a powerrequirement of said wearable electronic device.
 9. The wearableelectronic device of claim 1, wherein said power management unit furthercomprises an external power unit for providing external power to chargesaid energy storage device.
 10. The wearable electronic device of claim1, further comprising a casing containing said electronic display andsaid power management unit.
 11. The wearable electronic device of claim10, wherein said heat expelling unit is at a side portion of saidcasing.
 12. The wearable electronic device of claim 10, wherein saidcasing is in thermal communication with said heat collecting unit. 13.The wearable electronic device of claim 10, wherein said casing is inthermal communication with said heat expelling unit.
 14. The wearableelectronic device of claim 10, wherein said casing is in thermalcommunication with both of said heat collecting unit and said heatexpelling unit.
 15. The wearable electronic device of claim 10, whereinsaid casing is substantially waterproof or water resistant.
 16. Thewearable electronic device of claim 10, wherein said casing compriseslugs.
 17. The wearable electronic device of claim 16, wherein said lugsare in thermal communication with said heat expelling unit.
 18. Thewearable electronic device of claim 16, wherein said lugs dissipateheat.
 19. The wearable electronic device of claim 16, wherein said lugsdo not dissipate heat.
 20. The wearable electronic device of claim 10,wherein said casing further comprises a bottom subassembly.
 21. Thewearable electronic device of claim 20, wherein said bottom subassemblycomprises a conductive plate.
 22. The wearable electronic device ofclaim 20, wherein said bottom subassembly comprises said thermoelectricelement.
 23. The wearable electronic device of claim 20, wherein saidbottom subassembly comprises a conductive backing.
 24. The wearableelectronic device of claim 23, wherein during use said conductivebacking is in thermal communication with said body of said user.
 25. Thewearable electronic device of claim 20, wherein said bottom subassemblysnaps into said casing.
 26. The wearable electronic device of claim 20,wherein said bottom subassembly comprises threads and wherein saidbottom subassembly threads into said casing.
 27. The wearable electronicdevice of claim 26, wherein said threads are thermally conductive. 28.The wearable electronic device of claim 1, wherein said heat expellingunit includes one or more heat sinks.
 29. The wearable electronic deviceof claim 28, wherein said one or more heat sinks are heat fins.
 30. Thewearable electronic device of claim 1, wherein thermal communicationbetween said thermoelectric element and said heat expelling unit isprovided by at least one heat pipe.
 31. The wearable electronic deviceof claim 1, wherein thermal communication between said thermoelectricelement and said heat expelling unit is provided by a heat spreaderplate.
 32. The wearable electronic device of claim 1, further comprisinga control unit operatively coupled to said electronic display and saidpower management unit, wherein said control unit regulates display ofsaid information on said user interface.
 33. The wearable electronicdevice of claim 1, wherein said wearable electronic device is a watch.34. The wearable electronic device of claim 1, wherein said userinterface is a graphical user interface.
 35. The wearable electronicdevice of claim 1, wherein said user interface is an analog userinterface.
 36. The wearable electronic device of claim 1, wherein saidpower management unit is included in a clasp that secures saidelectronic display to said body surface of said user.
 37. The wearableelectronic device of claim 1, further comprising a flexible circuitoperatively coupled and in electrical communication with said electronicdisplay and said power management unit.
 38. The wearable electronicdevice of claim 37, wherein said flexible circuit is a flexible printedcircuit.
 39. The wearable electronic device of claim 37, wherein saidflexible circuit is a flexible-flat cable.
 40. The wearable electronicdevice of claim 1, further comprising one or more power generation unitsin electrical communication with said energy store device.
 41. Thewearable electronic device of claim 40, wherein said one or more powergeneration units are selected from the group consisting of a solar cell,an inductive coupling unit, a radio frequency coupling unit, and akinetic power generation unit.
 42. A method for using a wearableelectronic device, comprising: (a) activating said wearable electronicdevice comprising: a. an electronic display with a user interface fordisplaying information to a user; and b. a power management unitoperatively coupled with said electronic display, wherein said powermanagement unit comprises an energy storage device and at least onethermoelectric device in electrical communication with said energystorage device, wherein said thermoelectric device comprises (i) a heatcollecting unit that rests adjacent to a body surface of said user,which heat collecting unit collects thermal energy from said bodysurface of said user, (ii) a thermoelectric element in thermalcommunication with said heat collecting unit, and (iii) a heat expellingunit in thermal communication with said thermoelectric element, whichheat expelling unit expels thermal energy from said thermoelectricelement; (b) using said thermoelectric element to generate power uponflow of thermal energy from said heat collecting unit, across saidthermoelectric element and to said heat expelling unit, wherein at leasta portion of said power is stored in said energy storage device.
 43. Themethod of claim 42, wherein said wearable electronic device isintegrated with said power management unit.
 44. The method of claim 42,wherein said power management unit provides at least about 10% of apower requirement of said wearable electronic device.
 45. The method ofclaim 42, wherein said power management unit provides at least about 20%of a power requirement of said wearable electronic device.
 46. Themethod of claim 42, wherein said power management unit provides at leastabout 30% of a power requirement of said wearable electronic device. 47.The method of claim 42, wherein said power management unit provides atleast about 40% of a power requirement of said wearable electronicdevice.
 48. The method of claim 42, wherein said power management unitprovides at least about 60% of a power requirement of said wearableelectronic device.
 49. The method of claim 42, wherein said powermanagement unit provides at least about 80% of a power requirement ofsaid wearable electronic device.
 50. The method of claim 42, whereinsaid power management unit further comprises an external power unit forproviding external power to charge said energy storage device.
 51. Themethod of claim 42, wherein said wearable electronic device comprises acasing containing said electronic display and said power managementunit.
 52. The method of claim 51, wherein said heat expelling unit is ata side portion of said casing.
 53. The method of claim 51, wherein saidcasing is in thermal communication with said heat collecting unit. 54.The method of claim 51, wherein said casing is in thermal communicationwith said heat expelling unit.
 55. The method of claim 51, wherein saidcasing is in thermal communication with both of said heat collectingunit and said heat expelling unit.
 56. The method of claim 51, whereinsaid casing is substantially waterproof or water resistant.
 57. Themethod of claim 51, wherein said casing comprises lugs.
 58. The methodof claim 57, wherein said lugs are in thermal communication with saidheat expelling unit.
 59. The method of claim 57, wherein said lugsdissipate heat.
 60. The method of claim 57, wherein said lugs do notdissipate heat.
 61. The method of claim 51, wherein said casing furthercomprises a bottom subassembly.
 62. The method of claim 61, wherein saidbottom subassembly comprises a conductive plate.
 63. The method of claim61, wherein said bottom subassembly comprises said thermoelectricelement.
 64. The method of claim 61, wherein said bottom subassemblycomprises a conductive backing.
 65. The method of claim 62, whereinduring use said conductive backing is in thermal communication with saidbody of said user.
 66. The method of claim 61, wherein said bottomsubassembly snaps into said casing.
 67. The method of claim 61, whereinsaid bottom subassembly comprises threads and wherein said bottomsubassembly threads into said casing.
 68. The method of claim 67,wherein said threads are thermally conductive.
 69. The method of claim42, wherein said heat expelling unit includes one or more heat sinks.70. The method of claim 69, wherein said one or more heat sinks are heatfins.
 71. The method of claim 42, wherein thermal communication betweensaid thermoelectric element and said heat expelling unit is provided byat least one heat pipe.
 72. The method of claim 42, wherein thermalcommunication between said thermoelectric element and said heatexpelling unit is provided by a heat spreader plate.
 73. The method ofclaim 42, wherein said wearable electronic device comprises a controlunit operatively coupled to said electronic display and said powermanagement unit, wherein said control unit regulates display of saidinformation on said user interface.
 74. The method of claim 42, whereinsaid wearable electronic device is a watch.
 75. The method of claim 42,wherein said user interface is a graphical user interface.
 76. Themethod of claim 42, wherein said user interface is an analog userinterface.
 77. The method of claim 42, wherein said power managementunit is included in a clasp that secures said electronic display to saidbody surface of said user.
 78. The method of claim 42, wherein saidwearable electronic device comprises a flexible circuit operativelycoupled and in electrical communication with said electronic display andsaid power management unit.
 79. The method of claim 78, wherein saidflexible circuit is a flexible printed circuit.
 80. The method of claim78, wherein said flexible circuit is a flexible-flat cable.
 81. Themethod of claim 42, wherein the wearable electronic device furthercomprises one or more power generation units in electrical communicationwith said energy store device.
 82. The method of claim 81, wherein saidone or more power generation units are selected from the groupconsisting of a solar cell, an inductive coupling unit, a radiofrequency coupling unit, and a kinetic power generation unit.
 83. Amethod for manufacturing a wearable electronic device, comprising (i)assembling an electronic display with a user interface for displayinginformation to a user, and (ii) assembling a power management unit toyield said wearable electronic device, wherein said power managementunit is operatively coupled with said electronic display, wherein saidpower management unit comprises an energy storage device and at leastone thermoelectric device in electrical communication with said energystorage device, wherein said thermoelectric device comprises (i) a heatcollecting unit that rests adjacent to a body surface of said user,which heat collecting unit collects thermal energy from said bodysurface of said user, (ii) a thermoelectric element in thermalcommunication with said heat collecting unit, and (iii) a heat expellingunit in thermal communication with said thermoelectric element, whichheat expelling unit expels thermal energy from said thermoelectricelement, wherein said wearable device is configured such that duringuse, said thermoelectric element generates power upon flow of thermalenergy from said heat collecting unit, across said thermoelectricelement and to said heat expelling unit, wherein at least a portion ofsaid power is stored in said energy storage device.
 84. The method ofclaim 83, wherein said wearable electronic device comprises a casingcontaining said electronic display and said power management unit. 85.The method of claim 84, wherein said casing comprises a top side and abottom side and wherein said electronic display is disposed adjacent tosaid top side of said casing.
 86. The method of claim 84, wherein saidelectronic display and said power management unit are loaded into saidcasing from said top side of said casing.
 87. The method of claim 84,wherein said electronic display and said power management unit areloaded into said casing from said bottom side of said casing.